No. 52G] SEXUAL REPRODUCTION IN ANGIOSPERMS 619 



the experimenter in this field is yet to be demonstrated. 



On the other hand, while the cytoplasm may exist for 

 some time wholly apart from a nucleus, and although 

 during this separate existence the cytoplasm may re- 

 spond to certain stimuli, yet it can not do constructive 

 work — a phenomenon which seems to indicate roughly 

 the chief province of these two parts of the living cell. 



In the light of the foregoing analysis, we may now 

 consider some results obtained by indirect methods, and 

 through certain experiments. 



Since the declaration of 0. Hertwig in 1875, that fe- 

 cundation consisted essentially in the union of an egg 

 and a sperm nucleus, this doctrine has received general 

 acceptance. Some observers maintain that this idea 

 places undue emphasis upon the importance of the 

 nucleus, and claim that the cytoplasm is almost of equal 

 significance. In a recent publication Meves ('08) de- 

 scribes in great detail rod or thread-like bodies' in the 

 cells of the very young embryo of the chick, which he 

 designates as chondriosomes, and which he regards as 

 cytoplasmic bearers of hereditary characters. The same 

 author in 1904 described and figured similar rods and 

 threads as occurring abundantly in the tapetal cells of 

 Nymphaa alba. In the tapetal cells of the anther of 

 Ribes Gordonianum, Tischler ('06, p. 573) calls attention 

 to slender rods of varying length, which he designates 

 as chromidial substance, stating that they came out of 

 the nucleus. The writer has examined many thousands 

 of tapetal cells from various plants, fixed and stained 

 in a manner quite similar to that used by Meves, but 

 no such bodies have been found as those figured by this 

 author. It is not my intention to discuss this phase of 

 the subject from the* standpoint of zoological literature, 

 but it may be said that tapetal tissue is not the place that 

 a botanist would go to look for especially differentiated 

 hereditary substance. If hereditary substance, such as 



exists, 'iTseems very strange to a plant cytologic that 

 it can not be demonstrated in spore mother-cells, where, 



