﻿120 



MISSOURI BOTANICAL GARDEN. 



anything that lowers the vitality or interferes with the usual 

 life processes may inhibit the production of the archegonia. 



In some unpublished work by Shattuck at the University 

 of Chicago, upon the Marsiliaccae, it has been found that light 

 may inhibit the production of the megaspores. 



Spores were exposed to light from one side only to see if 

 they exhibited the polarity reported by Stahl for Equisetum 

 spores, but they gave only negative results. These same 

 cultures did show the marked heliotropism before mentioned. 

 This heliotropism was observed some years ago by Sachs, 

 Prantl, and others, and Wiesner (81) has worked out a 

 theory for such heliotropism based mainly upon turgor. 

 Leitgeb (76) reports positive heliotropism for liverwort 

 prothallia. 



To show that fern spores are capable of germinating in- 

 dependent of photo-synthesis, Schulz germinated spores in 

 air free of carbon dioxide, in the presence of light. He claims 

 in this germination the oil of the spore is converted into starch 

 by the stimulus of light. We may infer, from the fact that a 

 number of investigators have gotten starch formation in 

 darkness by cultivating spores in both organic and inorganic 

 solutions, that these solutions give a stimulus to the trans- 

 formation of the substances in the spore to starch. Laage 

 takes the position that there is no new formation of chloro- 

 phyll in germination in darkness. This is contrar}' to the re- 

 sults of Schelting upon germination of the spores of ferns, 

 and to Bittncr as well as Schimper upon the ferns in general. 

 From the fact that Equisetum spores, which contain an 

 abundance of chlorophyll, are able to germinate readily in 

 darkness at ordinary temperatures as shown by Heald, and 

 spores that have most chlorophyll form a young prothallium 

 with more chlorophyll than those with less chlorophyll, the 

 view of Laage is a very plausible one. It is noticeable that 

 the chlorophyll in the spore has a different form of plastid 

 from that of the young prothallium, the plastids of the 

 spore being much smaller and sometimes apparently little 

 more than granules. 



