106 EXTRACTS FROM CORRESPONDENCE. [April, 



this Moss^ for the purpose of ascertaining the nature of its inflo- 

 rescence, without great care and perseverance might very easily 

 be led astray. Supposing the specimen under examination was 

 a fertile one, he would not be long before he found near the base 

 of the fruit-stalk a number of perigonia, clustered together by 

 threes or fours, and near them he would find also true perichatia, 

 so he would naturally conclude that the plant he was investiga- 

 ting was a truly monoicous species, which however it is not strictly, 

 for on prosecuting the dissection he would meet, no doubt, with 

 synoicous flowers, containing an admixture of both antheridia 

 and archegonia, with their accompanying paraphyses. He thus 

 finds that his plant bears out the description assigned to it, of 

 being polygamous, that is, that each and all the kinds of inflo- 

 rescence known, exist together on the same plant. Now this is 

 exactly what occurred in the examples of H. speciosum, the only 

 difference being as to the relative number and disposition of the 

 kinds of flowers, the perigonia in this being rarely found, the 

 perich(£tia or simple female flowers not at all unfrequent, the 

 synoicous ones abundant. So far as that instance is of value, it 

 proves the plant liable to aberration, and undoubtedly throws 

 much uncertainty upon the distinguishing feature of H. remoti- 

 folium from H. speciosum, so far as the inflorescence is concerned. 

 But Mr. Wilson says that he should have no difficulty in distin- 

 guishing the two, apart from this circumstance ; but not having 

 seen the former, I cannot offer any opinion about it. As another 

 illustration of the occasional deviation in the mode of inflores- 

 cence, I may mention the very common H. rutahulum, in which, 

 Mr. Wilson tells me, synoicous flowers are not unfrequently pre- 

 sent. The plant is essentially a monoicous species, and this cir- 

 cumstance, with others, undoubtedly led to the discrimination 

 and detection of its very near ally H. rivulare, with which it 

 had long been confounded. In this latter the flowers are always 

 dioicous, thus affording an excellent test of the value of these or- 

 gans in assisting our diagnosis in the determination of closely 

 allied species. As also tending to show still more the necessity 

 of careful and unwearied attention, and of a persevering use of 

 the microscope in investigating species, I may venture to name one 

 or two incidents that have occurred to me very lately. A speci- 

 men of what was represented to be Hypnwn polygamum, was sent 

 to me lately by a friend ; from its general aspect I felt some 



