DEVELOPMENT OF THE PERITHECIUM. 25 



appendage is allowed to absorb moisture again it will straighten out, 

 and by drying again the bending may be repeated. Neger (68) 

 describes the repetition of the process a number of times as a result of 

 alternately moistening and drying the perithecia. The protoplast is 

 apparently living in the appendages of Phyllactinia till late in the ripen- 

 ing, at least till after they have performed their function in breaking 

 the perithecia loose. Neger's (69) experiments on old, dead perithecia, 

 in which he found the appendages still capable of executing their 

 hygroscopic motions, would seem to show that the living protoplast 

 is not essential for their proper functioning. The small number of 

 nuclei in the spinous appendage as compared with that in the actually 

 much smaller penicillate cell is notable and may perhaps be connected 

 with the difference in function of the two types of outgrowths. The 

 work of the penicillate cells is largely chemical in the formation of the 

 mucilaginous cap ; that of the spinous appendages is largely mechanical 

 in the bending motions they execute in tearing the perithecium loose 

 from its attachments. 



With the full maturity of the perithecium the development of the 

 spores in the asci begins. As a matter of fact, in sectioned material one 

 almost never finds spore formation beginning until after the perithecia 

 have broken loose from their original position and are lying wrong side 

 up and attached by the mucilaginous cap described above. It is pos- 

 sible, of course, that many perithecia may be overturned prematurely 

 in the processes of fixing, etc. Still only those in which the brush cells 

 have formed their mucilage will become fixed to the leaf and so appear 

 in the sections. The number of asci in a perithecium varies from 12 to 

 25. Median sections through the perithecium show sections of from 

 3 to 5 or 6 asci. The bursting of the perithecia and asci and the germi- 

 nation of the ascopores have not been observed for Phyllactinia, so far 

 as I am aware. 



