2 



A more detailed examination of the capsules shows a large number of gi- 

 gantic stomata of the phaneropore type crowded into the upper half of the hy- 

 pophysis, in the very region so actively sought by the flies. According to Dr. 

 Wiegmann these are the largest superficial stomata he has seen in any species 

 of moss: they measure with their guard cells .051 X .042 mm., while their open- 

 ing is .021 X .003 mm.; they can readily be detected with a X 10 hand lens. 

 Transverse and longitudinal sections of the hypophysis show below the stomata 

 a great abundance of cells rich in chlorophyll. It is probable that from these 

 stomata exudates the secretion which is lapped up by the flies. 



The flies captured while licking the hypophyses of Tetraplodon mnioides 

 were both sexes of a small anthomyid belonging to the genus Phorbia."^ I be- 

 lieve, however, that other muscid and anthomyid flies with short proboscis and 

 soft labella are also attracted by the capsules of this and other Splachnacece. 



The facts related above were quite new to me at the time. Meanwhile, 

 however, I have found that N. Bryhn, in Norway, has given an account of 

 similar relations between flies and certain European Splachnacece. Since my 

 interpretation diflfers in some respects from Bryhn's, a brief abstract of his in- 

 teresting paper^ may not be out of place here. His first observations were made 

 with Splachnum rubrum, an arctic species which grows on the excrement of 

 cattle. On a sunny day he noticed that a cushion of this moss attracted a swarm 

 of flies, some much like house-flies, also dung-flies and blow-flies,^ which alighted 

 on the cushion and crawled over the apophyses of the moss. In a half hour 

 he counted over 50 visits of flies to one cushion. Some of these insects were 

 caught and all were found to be covered with a yellow powder, which, upon 

 microscopic examination, proved to consist of spores of Splachnum. The flies 

 either were powdered uniformly over the under side, or they carried a large 

 patch of spores on the thorax. Bryhn also noticed that the flies upon leaving 

 the cushion of Splachnum often flew to fresh cow-dung nearby and wandered 

 over it. He thus came to the conclusion that they sow the spores of this moss 

 and further observations with other species of Splachnum and Tetraplodon con- 

 firmed this view. He also succeeded in making the spores of Splachnum rubrum 

 germinate on fresh cow-dung. 



The Splachnacece present in their mode of fructification many peculiarities 

 which, according to Bryhn, greatly facilitate the dispersal of their spores through 

 the agency of flies. In the case of Splachnum, for instance, a number of plants 

 form dense and rather large cushions, which are as much as 25 cm. across and 

 quite showy even from a distance. The seta is very long (as much as 20 cm.) 



^ These flies were kindly identified by Mr. J. A. Aldrich, Associate Curator at the U. S. Na- 

 tional Museum. 



3 Bryhn, N. Beobachtungen iiber das Ausstreuen der Sporen bei den Splachnaceen. Bio- 

 logisches Centralblatt. 17: 48-55. 1897- 



Bryhn's terms are "Dungfliegen" and "Schmeissfliegen. " Since no scientific names are 

 used it is difficult to know exactly what kind of flies are meant. Perhaps his "Dungfliegen" were 

 species of Scatophaga, while the "Schmeissfliegen" were probably of the common Calliphora vomi- 

 toria. 



