Artificial Parthenogenesis in Thalassema Melhta II9 



these through amceboid activity gave rise to a "veritable wilder- 

 ness of pseudopodia." Such fusions are rendered possible by the 

 destruction of the egg membrane, after treatment with salt solu- 

 tions, especially solutions of CaCU, and, with the heightening of 

 amoeboid movements, the naked masses of protoplasm show a 

 strong tendency to adhere whenever they come in contact. The 

 acid solutions, however, which I have used, never cause disap- 

 pearance of the membrane in Thalassema eggs, and this may 

 explain, in part at least, why fusion phenomena are entirely absent. 

 The eggs in which a membrane formation has been called forth 

 never adhere, but during the later stages of disintegration they 

 may become attached by their membranes to form clusters like 

 frog spawn; here, however, there is no protoplasmic fusion. 



VI OBSERVATIONS ON THE PRESERVED MATERIAL 



The internal changes involved in the artificial parthenogenesis 

 of Thalassema have been followed as closely as possible, and by 

 means of sections and total preparations many stages have been 

 examined throughout the entire period of development covered 

 by the material. 



In the study of the preserved material, however, serious dif- 

 ficulty is encountered in the attempt to determine the proper 

 sequence of changes taking place in the eggs and embryos, since, 

 as has been pointed out, the rate of development varies so greatly 

 in difl^erent eggs, even in the same culture, that a large number 

 of stages may be represented in each sample lot preserved. Fur- 

 thermore, the living egg can only be used as a control to a limited 

 extent, as it is too opaque to allow of any detailed examination of 

 internal changes, and an attempt to reconstruct successive stages 

 of development from a study of preserved material alone is 

 attended with more or less unsatisfactory results. Nevertheless, 

 with respect to most points, this uncertainty is reduced to a mini- 

 mum, and in cases where the parthenogenetic embryos coincide 

 in structure with those produced from fertilized eggs, it is fairly 

 safe to take for granted that the observed stages of development 

 have followed in their normal sequence. It becomes much grer ter, 



