The web page was created and compiled to guide the curious individual into the realm of "knowledge is power" and "breaking through." There is something to be said for just plain education, pure knowledge, and curiosity to know about animals and their natural landscapes from the perspective of WILD NATURE. That kind of knowledge is in all of the writing of George MacGinitie. It is also hoped that these web pages will help educate us all about the inter-relationships of the land and the sea, through the eyes of a gifted marine naturalist and marine biologist.

In 1928 I described the feeding habits of the gephyrean, Urechis caupo, in joint papers with Dr. W.K. Fisher, [1,2] in which he gave the classification and description of the worm. At that time this method of feeding was considered unique by those biologists who became acquainted with the paper; but I have since found that this method is not unique, for other animals use a simailar method of entangling their food, for example, Chaetopterus variopedatus and the tunicate, Diplosoma macdonaldi. In the case of many other animals in which the cilia have been credited with selective function of obtaining food, I have found that the mucus forms a plate through which water is strained, and actually the cilia furnish only the mechanical power for creating the currents. One reason why mucus has not heretofore been accredited with its important role is that it is perfectly transparent, unless heavily laden with food; and another reason is that investigators have used such materials as carmine, India ink, etc., which, in most cases, cause a cessation of the secretion of mucus. Hence, what the investigators have done is to make plots of the ciliary currents, which often were reversed from what they actually are during feeding operations.

I have found that the method of feeding in Chaetopterus is by the secretion of a slime bag or funnel through which all water entering the burrow during feeding passes. As the bag is being secreted at the top by the aliform notopodia, it is rolled into a ball at the bottom by the accesory feeding organ; but at all intervals secretion of slime ceases and this food ball is passed forward to the mouth, after which a new slime bag is formed. Therefore, the actual operation of food getting by Chaetopterus is quite different from that described Enders,[3] whose paper is by far the most complete of many written on teh natural history of this worm. It exemplifies a case in which mucus was overlooked in attempting to determine the feeding method of a plankton feeder.

A slime net is as efficient as any structure that one may imagine, for, though a dye in solution will pass through it as though it were not there, thte slime net will entrap the smallest particles which are visible by the aid of an oil immersion lens. With bottom feeding forms this microscopic material consists in large part of bacteria. in SCIENCE, 1932,[4] I gave an account of a successful feeding experiment in which a pure culture of bacteria was used by mud flat animal, and it is difficult to think of any structural device other than such a mucus net which would screen bacteria from water. The abundance and availability of marine bacteria for food have since been confirmed by ZoBell and Anderson[5] and other marine bacteriologists.

Apparently little is known of the chemical composition of mucin, particularly in the lower animals, and I believe nothing is known of its physical characteristics. A detailed account of the use of mucus by plankton feeders is in the process of preparation and should be ready for publication within the next year.

G. E. MacGinitie
Kerckhoff Marine Laboratory,
California Institute of Technology,
Corona Del Mar, California

FOOTNOTES
1. W.K. Fisher and G.E. MacGinitie, Ann. Mag. Nat. Hist., ser.10, Vol.1, pp.204-213, 1928.
2. W.K. Fisher and G.E. MacGinitie, Ann. Mag. Nat. Hist., ser.10, Vol.1, pp.199-204, 1928.
3. H.E. Enders, Jour. Morph., 20: 3, 479-532, 1909
4. G.E. MacGinitie, Science, 76: 1978, 490, 1932.
5. Claude E. ZoBell and D. Quentin Anderson, Bull. Am. Assoc. Petrol. Geol. 20: 3, 258-269, 1936.