OCTOBEE 18, 1912] 



SCIENCE 



527 



another must obviously have been greatly facili- 

 tated by their possession of wings, may in theory 

 appear plausible enough, but when tested on the 

 actual distribution of the species and subspecies it 

 proves to be of much less importance than com- 

 monly supposed; it rests, in reality, on the con- 

 fusion of two different things: the power of flight 

 no doubt would enable a bat to spread over a 

 much larger area than non-flying mammalia, but 

 as a matter of fact, only in a very few cases is 

 there any reason to believe that it has caused it 

 to do so.' ... A few of the more striking examples 

 may be mentioned here: a species of Pteroptis 

 inhabits the island of Pemba, south of Zanzibar, 

 but although the island is separated from Africa 

 by a channel only 35-40 miles wide, not this par- 

 ticular species only, but the whole genus is un- 

 known from any part of the adjacent continent;' 

 although absent from Africa the genus Fteropus is 

 distributed all over the Malagasy region,' and each 

 group of islands . . . has its own peculiar species, 

 intermigration between the groups of islands is 

 unknown; the Epomophorine section of fruit -bats 

 is distributed over the whole of the Ethiopian 

 region (eight genera, nineteen forms), but not a 

 single form has spread to any island of the 

 Malagasy region; the Fteropus melanoUis group of 

 [five] species is distributed over the Andamans, 

 Nicobars, Nias, Engano and Christmas Island 

 (south of Java), and the whole group is confined 

 to this chain of islands, no form having spread to 

 the neighboring Malay Peninsula or Sumatra. . . . 

 The fruit-bat faunas of the Malay Peninsula, 

 Sumatra and Borneo are closely interrelated, like 

 their mammalian faunas in general, but each has 



' The preponderance of bats over the character- 

 istic Indo-Malayan non-volant types in the fauna 

 of the Andaman and Nicobar Islands appears to 

 be an instance in which wings have played a part 

 in distribution (Miller, Proc. V. S. Nat. Mus., 

 XXIV., pp. 790-791, May 28, 1902) ; the presence 

 of a slightly modified species of Nycteris, a. char- 

 acteristic American type of bat, as the only in- 

 digenous mammal of the Hawaiian Islands is prob- 

 ably another case of the same kind. 



'Conversely, six species of European bats 

 (Myotis myotis, M. dasycneme, M. emarginatus, 

 Pipistrellus natusii, Eptesicus nilssonii and Ves- 

 pertilio murinus, although occurring on or near the 

 west coast from Brittany northward, are not known 

 to have become established in England. 



• It ranges eastward ' ' through the . . . Oriental 

 and Australian regions to the Samoa Islands." 



some distinct autochthonous forms of fruit-bats 

 (Borneo even two autochthonous [?]" genera), as 

 it has of other Mammalia; the Javan mammalian 

 fauna in general is more peculiar, both by the 

 absence of some of the forms found in Sumatra 

 and the Malay Peninsula, and by the greater per- 

 centage of autochthonous forms, and this is again 

 borne out by the Megachiropterine fauna of the 

 island . . . ; the Fteropus rayneri group is repre- 

 sented probably all over the Solomon Islands, but 

 it has differentiated into five distinct species, one 

 in the Bougainville group, a second on Villa 

 Lavella, a third in the New Georgia group, a 

 fourth on Guadalcanar and a fifth on San Cristobal. 

 This . . . tends to show that the present distribu- 

 tion of the Megachiroptera has not been influenced 

 to any great, and as a rule not even to any appre- 

 ciable, extent by their power of flight; if it had, 

 the fruit-bat fauna of one group of islands could 

 not, so commonly as is actually the case, differ 

 from that of a neighboring group or continent, 

 and the tendency to differentiation of insular 

 species or forms would have been neutralized by 

 the free intercourse between neighboring faunas. 

 Geerit S. Miller 



SPECIAL ABTICLES 



THE PRODUCTION OF SPERM ISO-AGGLUTININS 

 BY OVA 



I. If one allows unfertilized eggs of Ar- 

 hacia to stand in a quantity of sea-water that 

 does not exceed about ten times the volume 

 of the eggs, the sea-water soon becomes per- 

 ceptibly tinged with the red coloring matter 

 of the eggs. If now a few drops of such super- 

 natant sea-water be added to 2 or 3 c.c. of a 

 milky suspension of active sperm of the same 

 species, a strong agglutination of the sperms 

 immediately ensues, producing sperm-masses 

 easily visible to the naked eye. In the course 

 of three to five minutes reversal takes place, 

 the masses become converted into their con- 

 stituent cells, and considerable activity may 

 be observed after the reversal on microscopical 

 examination. The substance which produces 

 this phenomenon may be called a sperm ag- 

 glutinin, and since it is produced by the same 

 species, an iso-agglutinin. 



This basic phenomenon was studied in three 

 "Further exploration will probably show that 

 both occur on the peninsula or in Sumatra. 



