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SCIENCE 



[N. S. Vol. XXXIX. No. 1000 



tageous for the study of fertilization, since 

 the development and behavior of the repro- 

 ductive organs and cells could, without 

 elaborate preparation, be readily seen 

 under the microscope, and often followed 

 through in living material. Thus, Thuret 

 in 1853 for the first time saw the active 

 sperms attached to the egg of Fucus, and 

 in 1854 proved experimentally that only 

 eggs to which spermatozoids have had ac- 

 cess will germinate. He thus demonstrated 

 in this alga the correctness of Unger's un- 

 substantiated surmise (1837) that the 

 spermatozoids are the male fertilizing cells. 

 In (Edogonium, Pringsheim, in 1856 (p. 9), 

 watched the spermatozoid push into the 

 receptive tip of the living egg and saw the 

 •characteristic oospore wall formed in con- 

 ■sequence. This, except for the less satis- 

 factory observations made on Vaucheria 

 by the same worker a year previous, is the 

 first case recorded of the observation of the 

 actual union of male and female cells in 

 any plant. Such a union of the protoplas- 

 mic masses of the two sexual cells was soon 

 shown to be a characteristic feature of fer- 

 tilization in a number of algae. Thus de 

 Bary saw it in Spirogyra (1858), and 

 Pringsheim (1869) repeatedly observed the 

 gradual fusion of the motile gametes of 

 Pandorina. It was nearly thirty years 

 later, however, that this phase of fertiliza- 

 tion was first seen in seed-plants by Goro- 

 schankin and Strasburger. 



The workers on this problem were on the 

 lookout for further details of the proee^ of 

 fusion, and even knew rather definitely 

 what they were looking for, but failed to 

 discover it from lack of proper methods of 

 preparation of material. Thus, e. g., Stras- 

 burger, in 1877, carefully studied the proc- 

 ess of conjugation in Spirogyra and found 

 that "Hautschicht fuses with Hautschicht, 

 Kern plasma with Kernplasma" — "The 

 chlorophyll bands unite by their ends" — 



and then goes on to say of the feature that 

 evidently interested him most, "the cell 

 nuclei of both cells, however, become dis- 

 solved; the copulation product is without 

 a nucleus." Two years later, Schmitz 

 (1879), when studying hematoxylin-stained 

 material of this alga, was more fortunate. 

 He saw the two nuclei in the zygote, as he 

 says, "approach nearer and nearer, come 

 into contact and finally fuse to a single 

 nucleus." This observation by Schmitz is 

 an important one, for in it we have the 

 first clear statement that the nucleus of the 

 male cell passes over intact to the female 

 cell, there to fuse with the female nucleus. 

 Strasburger had, it is true, seen a 

 second nucleus fusing with that of the egg 

 in the archegonia of Picea and Pinus in 

 1877. He did not, however, really know 

 the source of this second nucleus, though 

 he suspected some relation to those that are 

 present earlier in the tip of the pollen 

 tube. These tube nuclei he says are dis- 

 solved just before fertilization, and then 

 just after fertilization, to quote (1877) : 



The male nucleus formed from the contents of 

 the pollen tube is found now near the end of the 

 tube, now near, or in contact with, the egg nu- 

 cleus. . . . The protoplasmic contents of the pollen 

 tube, I hold, passes through the (imperforate) tube- 

 membrane in a diosmotie manner. 



The fertilization of the gymnosperms, 

 because of their large eggs, pollen tubes 

 and nuclei, was then being studied by a 

 number of workers. One of these, Goro- 

 schankin, in 1883, was able to demonstrate 

 that in Pinus pumilio the pollen tube opens 

 at the end, and that through this pore the 

 two male cells pass bodily into the egg. 

 Goroschankin's mistake, in supposing both 

 male nuclei to fuse with the egg nucleus, 

 was corrected by Strasburger the follow- 

 ing year. The latter (1884) saw the same 

 bodily exit of both male nuclei from the 

 open pollen tube of Picea, but found only 



