284 MORPHOLOGY OF GYMNOSPERMS 



a number of cases in Larix europaea in which there is only one division 

 in the spore mother cells, resulting in two daughter cells that function 

 as microspores in the production of male gametophytes. This 

 condition finds its parallel in the development of certain female 

 gametophytes among angiosperms in which the second or both of the 

 reduction divisions occur as the first divisions of the ordinary game- 

 tophyte, which in such a case is really formed by two or four mega- 

 spores. This case of Larix suggests that the second reduction 

 division occurs in connection with the first division of the so-called 

 microspore, and that two spores enter into the formation of the game- 

 tophyte. The same observer has also reported (86) that the generative 

 cell is often free in the cytoplasm of the tube cell in Cupressus. In 

 Cunninghamia Miyake (147, 180) observed that in the division of the 

 generative cell no wall is formed, and the bulk of the cytoplasm is 

 organized in connection with the body nucleus, the stalk nucleus lying 

 free in the cytoplasm of the tube; and the same observation has 

 been made by Nichols (173) in Juniperus communis, and by Law- 

 son (175) in Sciadopitys. This reduction is like that described by 

 HiRASE for Ginkgo (p. 208) , and may possibly presage the final elimi- 

 nation of the stalk ceU. 



FERTILIZATION 



The tip of the pollen tube having reached the megaspore membrane 

 either penetrates it directly or flattens out upon it in a footlike expan- 

 sion, sending out a small branch to pierce the membrane. The body 

 cell divides about simultaneously with the central cell, so that the egg 

 and the male cell are produced a very short time before their fusion; 

 in Juniperus communis this period has been observed (173) to be 

 approximately three days. In the case of isolated archegonia (Abie- 

 tineae), the tube reaches the neck of the archegonium, crushes the 

 neck cells, and comes into contact with the egg; in the case of an 

 archegonial complex, the tube usually discharges its contents into 

 the common archegonial chamber. 



In addition to the two male cells, the tube contains the stalk and 

 tube nuclei, and in general all four bodies are discharged into the 

 cytoplasm of the egg, or into the chamber of an archegonial complex. 

 In the latter case, two eggs are usually fertilized from a single pollen 



