﻿PTERIDOGRAPHIA. 



Light and Germination of Spores. — The pro- 

 thallia of most ferns are found in moist shady places 

 and the ferns themselves are unusually adapted to a 

 shady habitat, but notwithstanding this the spores re- 

 fuse to germinate in darkness. A. C. Life who has 

 been carrying on some experiments along this line at 

 the Missouri Botanical Garden, writes in the 18th 

 Annual Report that the spores of the species he used 

 would not grow in darkness, but that germination pro- 

 ceded best in light of medium intensity. In very 

 weak light the prothallia tend to take on a ribbon 

 shape, while stronger light gave the. usual heart- 

 shaped form. Strong light seems to favor the pro- 

 duction of archegonia and weak light produces anthe- 

 ridia, only. The spores of all the species experimented 

 upon contain chlorophyll which very readily accounts 

 for the stimulus that light gives to germination. A 

 point which none who have investigated the germina- 

 tion of fern spores seem to have kept in mind is that 

 all ferns do not have the same habitat. It may be 

 assumed that with ferns which normally grow in the 

 open, a higher light intensity for germination would 

 be required than with ferns that naturally grow in the 

 shaded ravines. A higher temperature, also, will 

 probably be found more congenial to the spores of 

 tropical ferns than to those of colder regions. 



Development of Ophioglossum. — In ordinary 

 ferns a new plant is produced by a fertilized egg which 

 divides, into four regions that produce the stem, leaf, 

 root and foot respectively, but in some cases some of 

 these organs are omitted. According to Campbell, 

 who has been studying the Ophioglossaceae, there are 



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