August 23, 1912] 



SCIENCE 



255 



the transfer of fluid is in itself the essential 

 or " inogenetic " part of the process. It is of 

 course obvious that any theory which (e. g.) 

 regards contraction as due to a swelling of the 

 isotropic segments by fluid absorbed from the 

 anisotropic — as discs of gelatin or fibrin swell 

 in acidulated water — must require that the 

 interchange of fluid should be rapid and 

 promptly reversible; hence that part of the 

 present interpretation which regards the struc- 

 ture of striated muscle as essentially a means 

 for facilitating transfer of fluid within the 

 cell is equally consistent with this latter 

 theory. Nevertheless the point of view that 

 regards absorption of water by an acidulated 

 sheet of gelatin as the analogue of what occurs 

 in muscular contraction is radically different 

 from that set forth in this paper, according 

 to which the energy of contraction is the 

 transformed surface-energy of the ultimate 

 structural elements or colloidal particles (sub- 

 microns) composing the fibrils. There is un- 

 doubtedly a movement of fluid between the 

 muscle-segments during contraction; but this 

 fact in itseK is consistent with either of the 

 two theories just contrasted. The decision 

 between the two must be made on the basis 

 of other evidence. 



Ealph S. Lillie 

 Marine Biological Laboratory, 

 Woods Hole, ^ 



June 7, 1912 



FERTILIZATION OF THE EGGS OF VARIOUS INVERTE- 

 BRATES BY OX-SERUM 

 I 



The chemical method of artificial partheno- 

 genesis has thus far been worked out with any 

 degree of completeness, only for the Cali- 

 fornian sea urchin, Strongylocentrotus pur- 

 puratus. In this form it was shown by Loeb 

 that the process of fertilization is composed of 

 two entirely different phases. The one is an 

 alteration or destruction of the surface layer 

 of the egg. This alteration of the cortical 

 layer may or may not result in the formation 

 of a fertilization membrane. The alteration 

 of the surface can be brought about by a 

 great many different means, all of which have 



a cytolytic effect. The superficial cytolysis 

 starts the development of the egg but leaves 

 the latter with a tendency to perish during the 

 further development. The sickly condition is 

 remedied by a second treatment of the egg, 

 which may consist in putting the eggs for 

 about from 30 to 50 minutes into hypertonic 

 sea water of a certain concentration. If taken 

 out of this solution, the egg develops prac- 

 tically normally. 



Experiments on heterogeneous hybridization 

 which Loeb carried out, furnished the evidence 

 that the spermatozoon also causes the develop- 

 ment of the egg by carrying two agencies into 

 it, one of which is a cytolytic substance, a 

 lysin, which causes the membrane formation. 



Lysins are contained not only in the 

 spermatozoon but in all the cells and in the 

 blood of any animal. Loeb found five years 

 ago that the blood of a worm, Dendrostoma, 

 calls forth membrane formation in the unfer- 

 tilizing egg of the sea-urchin. This blood re- 

 tained its fertilizing power when diluted as 

 much as several hundred times with sea water. 



The same author found subsequently that 

 the blood and tissue extract of many animals 

 had the same effect, e. g., the blood of cattle. 

 The fact that the blood of each female does 

 not cause the parthenogenetic development of 

 its ovra. eggs, Loeb explained by the theory, 

 that while the lysins contained in the blood of 

 foreign species can diffuse with comparative 

 ease into the egg and the cells of an animal, 

 the lysins contained in its own blood are pre- 

 vented from such a diffusion. 



It was found impossible to cause the de- 

 velopment of the eggs of all female sea- 

 urchins by means of foreign blood. This difS- 

 culty was overcome by treating the eggs with 

 strontium chloride before they were exposed 

 to the foreign serum. If the sea-urchin eggs 

 were put for a short time into a I or A Jf so- 

 lution of strontium chloride, a subsequent 

 treatment with ox blood caused them all to 

 form fertilization membranes. When subse- 

 quently treated for a short time with hyper- 

 tonic sea water, most of the eggs developed 

 into normal plutei. 



