472 



SCIENCE 



[N. S. Vol. XXXIX. No. 1004 



2. Proteins, if present at all, do not necessarily 

 come from the eggs, and are extremely dilute. Re- 

 ducing substances seem to be absent. The agglu- 

 tinin is heat-resistant. A purple compound, ap- 

 parently specific for Arbacia, is formed when the 

 sperm, the eggs or the agglutinin itself undergo 

 certain changes. More soluble substances are se- 

 creted at the moment of fertilization than before. 

 This, together with the fact that the volume of the 

 eggs is smaller after fertilization, constitutes new 

 and strong evidence in favor of the contention that 

 fertilization involves an increase in permeability. 

 From this it need not follow that fertilized eggs 

 are more permeable than unfertilized. In fact this 

 is not very probable. 



3. Egg-secretion as well as egg-extract, in cer- 

 tain concentrations, retards development. NaOH 

 in certain concentrations does not accelerate cleav- 

 age, but may even depress it. In the same concen- 

 trations, it accelerates the development from the 

 blastula to the pluteus. Egg-secretion -f NaOH in 

 the above concentrations retards the cleavages 

 much more than either used separately. One can 

 draw no inference from these experiments as to 

 how the egg-secretion acts in retarding develop- 

 ment. 



The suggestion that development is initiated as 

 the result of a disturbance in equilibrium in which 

 substances antagonistic to oxidation are eliminated 

 is possible. It is equally possible that the removal 

 of the substances lost allows other equally impor- 

 tant processes to be set up. The initiation of devel- 

 opment is identical with the initiation of cell di- 

 vision. For this process fertilization, even if it 

 involves all that Lillie's theory includes, can not 

 be considered essential, since somatic cells divide 

 without it. This does not imply that the mechan- 

 ism of fertilization may not be exactly as F. E. 

 Lillie supposes, but the possibility that the initiation 

 of cell division depends on other processes which 

 also occur at the moment of fertilization remains. 

 Neither these suggestions nor the facts on which 

 they are based appear to the author out of har- 

 mony with existing theories. A full discussion will 

 be published in a forthcoming issue of the Biolog- 

 ical Bulletin. 



Feeding Sabits of Amosha: Asa A. Schaeffee. 



The method of investigation is very simple. A 

 very small particle of the substance to be tested 

 was placed in the amceba's path by a very finely 

 drawn out glass needle. Camera lucida drawings 

 were then made at frequent intervals in order to 

 record the behavior accurately. A large number of 



substances were used: small animals and plants, 

 isolated proteins, carbohydrates, fats, carbon, 

 glass, carmine, etc.; also capillary tubes filled with 

 solutions of various substances. 



It was found that the amoeba exercises a consid- 

 erable degree of precision in selection while feed- 

 ing; objects of food value being eaten while those 

 valueless as food were rejected. However, of the 

 substances eaten, carmine, india ink and uric acid 

 are probably valueless as food; and of the sub- 

 stances refused, casein, gelatin, lecithin and zein 

 are food substances. What the basis is upon which 

 amcEba selects its food can not be stated. But 

 amosba eats everything that moves. If a particle 

 of carbon or of glass or other substance is properly 

 agitated by means of a glass needle, such particle 

 will be eaten. 



Amoebas react to objects at a distance, whether 

 soluble or insoluble. The maximum distance 

 through which an amteba may sense an insoluble 

 object 20 microns in diameter is from 40 to 60 

 microns. 



Some amceba may be led about by "tickling" 

 with an extremely fine glass needle. A typical 

 ' ' food cup ' ' may also be produced in this way. 



The behavior of amosba while feeding is subject 

 to very great variation. 



ClKinges in Pattern and Color in Fishes, With Spe- 

 cial Reference to Flounders: S. O. Mast. 

 Abstract in Science, Vol. XXXVIII., page 699. 

 The Seaations of the Orb-weaving Spider, Aranea 

 Cavatica; to Rhythmic Vibrations of the Web: 

 W. M. Baesows. (Illustrated with lantern 

 slides.) 



It was found by using vibrating tuning forks 

 and an electric vibrator that when one part of the 

 spider's web is set in rhythmic motion (24-100 

 vibrations per second amplitude 3-12 mm.) the 

 sjjider orients, advances rapidly toward the vi- 

 brating point, and attacks the vibrating instru- 

 ment, even biting and throwing web on it. This 

 positive reaction was not obtained when irregular 

 vibrations were used as the stimulus. When a 

 double or T-shaped vibrator was used the spider 

 oriented and advanced directly between the two 

 vibrating points. The author considers this re- 

 sponse a tj^pical tropism and suggests the name 

 ' ' tonotaxis ' ' to designate it. 



Secretion in the Protosoan, Folliculina: E. A. An- 

 drews. 



This specialized Stentor secretes a transparent 

 ease of green or brown color, resembling a stock- 

 ing in. form. The rounded foot has one flat side 



