No. 472] POLLEN GRAIN VARLATION 255 



Among numerous species of angiosperms and a few gynnio- 

 sperms Fritzsche ('36, p. 693) described and figured the pollen 

 grains of Pinus sylvestris and Pinus larix (Larix europcra). The 

 terms he used for the different cells formed in the pollen grains 

 were totally different from those now in use. He did not regard 

 the bodies seen as cells, nor did he have any knowledge of their 

 function or homology. His figures show, however, a remarkable 

 accuracy of observation, if we take into consideration the state 

 of knowledge of his time, and the comparatively poor microscopes 

 and crude microscopical methods. He examined the pollen 

 grains in oil of lemon (Citronenol), and he undoubtedly saw one 

 of the disintegrating prothallial cells in both Pinm sylvestris and 

 Larix europosa. His Plate 3, Figure 10, shows this for the former, 

 and Figure 14 for the latter. In Larix, besides the disintegrating 

 prothallial cell, he showed the cells which were later called the 

 "stalk" and "body" cells. The latter, Fritzsche called the cen- 

 tral vesicle, and the other two cells he called "Zwischenkorper." 



Later investigations have shown that in Larix, and sometimes 

 in Pinus also, there are two prothallial cells cut off which later 

 may disintegrate wholly or partly. It is not safe, however, to con- 

 clude that these genera vary in the number of prothallial cells 

 formed merely because Fritzsche did not see two of them while 

 other writers have done so. When we remember the difficultit - 

 encountered by later observers equipped with much better nncro- 

 scopes than Fritzsche could have had in 1836, the wonder is that 

 he saw so much. 



Meyen ('39) pointed out that Fritzsche 's "Zwischenkorper " 

 w^ere really cells, and that one of them served as stalk of attach- 

 ment to the larger cell. This was probably the first application 

 of the term "stalk" to this cell ('39, p. 189). 



For about two decades after this time the literature concerning 

 the pollen grain is occupied mostly with evidence for and against 

 the view of Schleiden, advanced in is;^7, that the embryo has its 

 origin in the pollen tube. Schacht (':>-', p. 407 1 wcnr so tar a. to 

 say that the pollen is the egg of the plants, an.i that tln-rv is no real 

 analogy between am'mal and plant fertilization among phanero- 

 gams. 



Hugo von Moll! T..") . I lotnieister (o5), and others opposed 



