37 



for half an hour, after which time most of the shells were 

 cracked. Some of these frozen eggs were then incubated 

 immediately at 38°, others were kept in a cool chamber 

 and incubated after one day, and others, finally, were kept 

 for 3 days before being incubated. All of them, together 

 with 6 control eggs in each set, were opened after a 3-day 

 incubation. About one third of the eggs in each of the 

 different series of experiments presented embryos, al- 

 though badly deformed, while the other two thirds con- 

 tained blastoderms extended over the yolk, but showed no 

 embryo formation. The author concludes that freezing 

 did not prevent cell proliferation liut tended to inhibit cell 

 differentiation. 



As a thoroughly worked out investigation on the death 

 temperatures of the chicken egg and on the time required 

 for death at various temperatures we shall describe Mo- 

 ran 's work (1925) . He placed 100 eggs in a constant tem- 

 perature room at - 2.9° and 100 in another room at - 4.6°. 

 Every few hours some eggs were taken out and tested, the 

 power of incubation being taken as the index of vitality. 

 In a previous determination of the velocity of cooling, 

 made with a thermo-couple, it was found that 24 hours 

 elapsed before the center of the egg reached - 2.9° and 30 

 hours before it reached -4.6°. The general results were 

 that some eggs were still capable of developing after hav- 

 ing been for nearly 47 hours at -4.6° and 118 hours at 

 - 2.9°. But even above zero the power of incubation was 

 soon destroyed. The limit of the time that the eggs could 

 be stored at 0.7° was 10 days and at 10.4°, 34 days. In 

 these experiments cooling and Avarming were graded and 

 slow. Moran concludes that the germination capacity is 

 probably destroyed immediately at -6° to -7°, while 

 at the higher temperatures death requires increasingly 

 longer times. It seems evident that all the eggs studied 

 were subcooled ; the question of whether or not the chicken 

 egg withstands congelation, is left untouched in this work. 

 3. Spores. Strasburger {Jena. Ztschr. f. Naturwiss., 

 12, 612, 1878) observed swarm spores of the algae, Haema- 



