76 A. J. GOLDFARB. 



minutes after fertilization, many did not segment at all or 

 cleavage was irregular. It was evident that when eggs were 

 shaken about two minutes after fertilization, the fertilization 

 membranes were cast off most readily, and with the least dis- 

 turbance to subsequent development. 



The minimum shaking found necessary to remove the fertili- 

 zation membranes from all or nearly all the eggs was about one 

 and a half minutes. Figs. I and 2, drawn from life immediately 

 after the shaking, represent the eggs freed from their membranes. 

 In Figs. 3, 4 and 5, the eggs have only partially protruded from 

 their membranes. Such extruded parts varied considerably in 

 size, and were often equal to the part within the membrane, 

 Fig. 5. Such " extra-ovates " were the same in kind, as those 

 produced by Loeb' 94, with dilute solutions of sea water. When 

 the egg was divided into two equal or nearly equal parts, twin 

 embryos were formed which often reunited into a more or less 

 single larva. When the extra-ovate was small, as in Figs. 3 

 and 4, it was most frequently sloughed off and developed into 

 an atypic blastula or, in some instances, an atypic gastrula. 

 Practically all the eggs were elongated but this change of shape 

 was only temporary, and subsequent development was normal. 



The rate of development was unaffected by the treatment. 

 This may be seen in Table I. in which the rate of development in 

 each culture is compared with its corresponding control. It is 

 seen that in certain of the experiments the eggs developed more 



TABLE I. 



The eggs were violently shaken for about two minutes. Their rate of develop- 

 ment when compared with the controls showed no material difference. 

 No. Result. 



20 Shaken lot developed at about the same rate as the controls. Many never 



reached the pluteus stage. 

 I2a Shaken lot never reached the pluteus stage. 



b Shaken lot behaved like the controls. 

 37 Shaken eggs developed taster, and more of them reached the pluteus stage; than 



the controls. 

 15 Shaken eggs were like the controls, lived longer, but contained more atypic 



larvae. 



14 Shaken and control lots the same. 



25 Shaken and control lots the same. More small-sized larvae in shaken lot. 

 34 Shaken and control lots the same. More small-sized larvae in shaken culture. 



