580 STUDIES IN GENEKAL PHYSIOLOGY 



resembled the one described by Morgan to such an extent 

 that Mathews came to the conclusion that it was not the ren- 

 net which acted in his experiments, but the salts in the ren- 

 net tablets. In other words, it was practically the increase 

 in the concentration of the sea-water which brought about 

 the segmentation of the unfertilized egg, just as in Mor- 

 gan's experiment. 



There are some earlier observations concerning the fact that 

 unfertilized eggs may show the beginnings of segmentation. 

 Hertwig mentions, 1 that the eggs of Arthropods, Echino- 

 derms, and Annelids show a beginning of segmentation 

 when left in sea-water for a long time (about twenty 

 hours). Tichomirof is quoted as having produced arti- 

 ficially a beginning of development in the eggs of Bombyx. 

 But these eggs are naturally parthenogenetic. Nussbaum 2 

 has repeated these experiments, and, as far as I can see, the 

 unfertilized eggs of Bombyx seem to develop naturally just 

 as well as with the treatment given them by Tichomirof. 

 There is a statement by Dewitz 3 that treatment with cor- 

 rosive sublimate causes the eggs of a frog to show a begin- 

 ning of segmentation, but, if, I am not mistaken, Dewitz 

 made no sections through these eggs, and he himself ex- 

 pressed his doubts to me as to whether there was a real 

 segmentation, or whether the surface of the egg simply 

 resembled that of segmented eggs. 



Kulagin recently made the following statement: "I ex- 

 posed unfertilized eggs of fish and amphibians to diphtheria 

 antitoxin, and noticed in many the process of segmentation."^ 

 As this one sentence is all he has published about his ex- 

 periments, it is impossible to express an opinion concerning 

 them. If there was a real segmentation, it still remains an 



1 O. HEKTWIG, Die Zclle und die Gewebe, Vol. I, p. 239. 



2 M. NUSSBAUM, Archiv fur mikroskopische Anatomie, Vol. LIII (1899), p. 444. 

 i J. DEWITZ, Biologisches Centralblatt, Vol. VII (1887), p. 93. 



* KULAGIX, Zoologischer Anzeiger, Vol. XXI (1898), p. 653. 



