I 



d 



66 BOTANICAL GAZETTE [kovember 



f 



13, 14); Sagittaria (Schaffner 39), Convallaria (Wiegand 46), 

 Asclepias (Frye 21), and Hamamelis (Shoemaker 41), If the tube 

 cell represents the wall cells of the antheridium, this wall is a relict of 

 the time w^hen there was a complete separation between spermatoge- 

 nous and wall tissue (Coulter and Chamberlain 18). This differ- 

 ence was shown not only by separating walls but by reaction to stains; 

 and the latter difference still remains in the pollen grain after the 

 wall disappears. 



Double fertilization. — In looking over my material it seems 

 strange that double fertilization was first reported less than a decade 

 ago, when Nawaschin (33, 34) made his announcement. In my 

 material double fertiUzation was observed in hundreds of instances; 

 in fact there would be some difficulty in finding fertilization without 

 some suggestion of triple fusion; it was as evident in every respect as 

 the fertilization of the egg. How^eveT;, it w'as stated above that in 

 some cases it may fail to take place; and it would not seem unlikely 

 that in some orchids triple fusion always occurs and in others it may 

 be rare or omitted altogether, as indicated by Strasburger and 



Nawaschin. Nawaschin thought that in the failure of triple 



f 



t 



t 



rm 



orchids, but it is evident that the little or no endosperm of this family 

 must be referred to other causes. It may be accurate enough for 

 taxonomic purposes to say "no endosperm" in the orchids, as in 

 a recent manual (42), but it is not an exact statement. 



AND 



Some 



tant evidence on this much-discussed question was obtained- This 

 condition was first reported in plants by Kruch (30), w^ho worked with 



me 



little attention and seems to have been entirely overlooked by later 

 workers. Kruch showed the sperm entering the egg and segmenting 

 in the upper part of the cytoplasm, while the chromatin of the egg- 

 nucleus segments near the center, each showing eight chromosomes, 

 and the nuclei were not even in contact. Blackman (2), working 

 with Pintis sylvestris, figured tw^o groups of chromosomes in the first 

 di\Tsion of the fertihzed egg and says: ''there can be little doubt that 

 these bodies are really the chromosomes of the two (male and female) 

 nuclei." In his summary he makes the Dositive statement that they 



