250 Mr. W. H. Lang. Preliminary Statement on the 



3. Whereas direct excitation of the anterior roots in the dog pro- 

 duces, as a resultant movement, extension of the lower limb, the 

 resultant movement produced from the kinoesthetic centres of excita- 

 tion of the posterior roots is always flexion. In the monkey there is 

 not this apparent antagonism, because stimulation of the anterior 

 roots in that animal brings out a differentiation of flexion and exten- 

 sion, although excitation of the posterior root gives flexion alone. 



"Preliminary Statement on the Development of Sporangia 

 upon Fern Prothalli." By WILLIAM fl. LANG, M.B., B.Sc., 

 Lecturer in Botany, Queen Margaret College, and Robert 

 Donaldson Scholar, Glasgow University. Communicated 

 by D. H. SCOTT, M.A., Ph.D., F.R.S., Honorary Keeper of 

 the Jodrell Laboratory, Royal Gardens, Kew. Received 

 September 14, 1896. 



The observations recorded in this paper were made in the course of 

 an investigation into the relation existing between variability in the 

 fern plant and apogamy in the prothallus. This research was under- 

 taken at the suggestion of Professor Bower, F.R.S., and has hitherto 

 been conducted in the Jodrell Laboratory, Royal Gardens, Kew. 

 To Dr. Bower and Dr. Scott I am indebted for valuable assistance 

 and advice. 



In two of the species investigated, Scolopendrium vulgare, L., and 

 Lastrcea dilatata, Presl., sporangia were borne upon the prothallus. 

 In the former they were sometimes associated with apogamous 

 development of the sporophyte, the details of which differ, however, 

 from previously recorded cases of apogamy. As a considerable 

 period must elapse before an amount of material sufficient for the 

 complete study of details of development can be obtained, it appeared 

 advisable to describe the results obtained from the material at 

 present available. Cultures are about to be commenced in the 

 Glasgow Botanic Gardens for the further study of these abnormal 

 prothalli. 



The prothalli of the two species investigated will first be de- 

 scribed, and the theoretical bearing of the results briefly considered. 



Lasfrcea dilatata, PresL, var. cristata gracilis, Roberts. 



The spores from which the cultures of this fern were made were 

 obtained from a plant in the collection of Mr. C. T. Druery, F.L.S., 

 who kindly supplied me with material. This variety was found 

 wild in Carnarvon in 1870. Spores were sown in the first week 

 of November, 1895, upon a carefully sterilised soil, consisting of 



