BULLETIN 
OF THE 
TORREY BOTANICAL CLUB. 
Vol. XVIII] New York, March 10, 1891. (No. 3. 
A Study of the Apical Growth of the Prothallium of Ferns with Reter- 
ence to their Relationships. 
By DoucLas H. CAMPBELL. 
(Plate CXV.) ; 
In January of last year I published in the Botanical 
Gazette* a paper on the affinities of the Filicineze suggested by a 
similar one by Bowert in the Annals of Botany, the object of my 
paper being to defend the older theory of the origin of the ferns 
from the Hepatic, as opposed to the later theory of Bower} and 
others that the ancestral forms of the pteridophytes were alga-like 
forms similar to the filamentous prothallium of certain Hymeno- 
phyllacezee which are regarded as the most primitive of living 
Filicineze. 
Having been engaged for some time past in the further study 
of this problem, a number of facts have been collected which may 
- serve to throw some further light on this most interesting ques- 
tion, 
As is well known, the prothallium of most ferns bears a most 
striking resemblance to certain thallose liverworts,—-indeed, so 
striking is the resemblance that sometimes a miscroscopic examin- 
ation is necessary to distinguish them, and when the prothallia 
remain unfertilized they may reach a size considerably surpassing 
many of the smaller liverworts.§ 
In its earlier stages the young fern-prothallium usually grows 
* Campbell—On the affinities of the Filicinee. Bot. Gaz. Jan. ‘90. 
+ Bower—The Comparative Examination of the Meristems of Ferns as a Phyto- 
genetic Study. Annals of Botany. 
+ Bower—1. c. p. 386. 
$ Goebel—‘‘ Outlines.” _p. 199. 
