96 



by means of a pair of needles. Subsequently one can use 

 staining fluids or occasionally some dilute chloral hydrate to 

 make relations plainer. 



If one injures the embryosac one usually obtains nothing 

 but unclear, mixed up pictures, especially for the later stages. 

 A number of poUentubes may reach the embryosac at about 

 the same time, their difl'erent points of penetration may be 

 established by gently turning the embryosac around and around. 

 Of every pollentube the generative nuclei copulate with two 

 nuclei of the fertil part of the embryosac, so that finally by 

 dividing the number of large nuclei seen in the embryosac by 

 two, one knows the number of pollentubes that have penetrated 

 into the embryosac. Owing to this cause the large copulated 

 nuclei are found in pairs. Fig. 45 PI. VII, shows two such pairs 

 of nuclei lying near to the ends of the pollentubes belonging 

 to them. The next step takes place by the large nuclei sur- 

 rounding themselves with a rather dense mass of protoplasm, 

 which can be plainly distinguished from the protoplasm of the 

 embryosac. (The two nuclei at the left in fig. 45 PI. VII). Sub- 

 sequently these products of copulation surround themselves 

 with a membrane and I will now call them Zygotes (the two 

 at the right in fig. 45 PL VII). In this same picture the mem- 

 branes can be plainly distinguished owing to the action of the 

 alcohol which caused the protoplasm to contract. These zygotes 

 may now attach themselves to the wall of the embryosac or 

 they may become concrescent with the end of the pollentube 

 (fig. 46, 47, 48, 49, PI. VIII). In the latter instance the whole 

 frequently ressembles, as can be seen from the pictures a pro- 

 embryo forming the embryo, the pollentube simulating a sus- 

 pensor. In the young zygotes peculiar spindle like structures 

 occur sometimes, suggesting a throwing out of polar bodies, 

 (cp. fig. 44 PI. VII). It seems to me worth while to follow this 

 question up and I expect to deal with it as soon as I have 

 obtained the artificially fertilised material mentioned before. 



