422 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



destroyed, arid actually aiding the stronger ones by serving 

 them as food until they could pass through their changes 

 and escape to other regions where food was more abundant." 



A case of mimetic coloring in tadpoles is recorded by 

 Sarah P. Monks in the American Naturalist for October. 

 She finds that the tails of the tadpoles resemble the sub- 

 merged lower leaves of a plant, Ludovidgia palustris, in 

 color, width, and shape. The resemblance in color was so 

 striking that a friend, who was not on the lookout for analo- 

 gies, mistook a leaf for a tadpole. 



Mr. Darwin has referred to two species of Orthoptera, al- 

 lied to JPterocJtroza illustrata and P. ocellata, remarkable for 

 their perfect imitation of dead leaves, which was carried out 

 in the venation of the wings, even to microscopic details, as 

 compared w T ith the ribs and veining of leaves. 



A number of instances of protection resemblance are given 

 by Mr. Meldola, in the Annals and Magazine of Natural His- 

 tory. Among others is the case of an Indian Mantis, which 

 resembles a flower. 



General Embryology. 



Recent observers such as Bfltschli, E. Van Beneden, Fol, 

 Hertwig, Strasburger, and Calberla have thrown a great deal 

 of light on the phenomena of the maturation and impregna- 

 tion of the es;^. Their conclusions have been summarized 

 as follows by Mr. F. M. Balfour, the eminent English embry- 

 ologist. In what may probably be regarded as a normal 

 case, the following series of events accompanies the matura- 

 tion and impregnation of an egg: (1) Transportation of the 

 germinal vesicle to surface of the egg; (2) absorption of the 

 membrane of the germinal vesicle and metamorphosis of the 

 germinal spot; (3) assumption of a spindle character by the 

 remains of the germinal vesicle, these remains being probably 

 largely formed from the germinal spot; (4) entrance of one 

 end of the spindle into a protoplasmic prominence at the 

 surface of the egg ; (5) division of the spindie into two 

 halves, one remaining in the egg, the other in the promi- 

 nence ; the prominence becomes at the same time nearly 

 constricted oft* from the egg as a polar cell ; (G) formation 

 of a second polar cell in the same manner as the first, part of 

 the spindle still remaining in the egg; (7) conversion of the 



