MICROSPHMRA FRIESII. 55 



6. Examine younger and younger perithecia to as early a 

 stage as possible. Draw. 



D. The very simple ORGANS OF FERTILIZATION, 



the beginning of the perithecia, can rarely be found 1 ; if 

 seen, notice 



a. The larger axial cell, the carpogonium. 



b. The smaller lateral cell, applied closely to the car- 

 pogonium, the antheridium. 



^. Draw. 



ANNOTATIONS. 



The group of Carpophyta to which Microsphaera 

 belongs, a very large one, is characterized by having a 

 special covering for the spores, developed as a result of 

 fertilization. Except in some of the higher forms, the 

 fertilization takes place much as in the Oophyta, but the 

 subsequent development is very different, for an out- 

 growth of branches from the portion immediately 

 below the organs of fertilization at once arises which 

 eventually envelops the forming spores and develops 

 into the body of the fruit. 



It is altogether likely that Microsphaera has reached 

 an advanced parthenogenetic stage, i. e. the fruits are 

 largely produced without the transfer of protoplasm 

 from the antheridium to the carpogonium, which consti- 

 tutes fertilization. On this account some other plants 

 better illustrate the fertilization and the early growth of 

 the fruits than the one used ; the student is advised 

 to examine these features, if possible, in Nemalion, one 



1 To get some idea of their shape, examine figs. 188 and 189 in Bessey's 

 Botany, p. 280-1. 



