388 



SCIENCE 



[N. S. Vol. XLIV. No. 1133 



about. But the value to the species of the 

 rhythmic-light pulsation of the fire-flies is not 

 obvious, and as it is doubtful if the emission of 

 phosphorescent light is under the control of the 

 insect, or is merely a simple automatic process of 

 metabolism, its synchronism is a most puzzling 

 fact. 



Dr. Hermon C. Bumpus wrote me that some 

 years ago in riding from Falmouth to Woods 

 Hole his attention was arrested by noticing in 

 a field along the road a large number of fire- 

 flies flashing synchronously. 



Edward S. Morse 



A FURTHER NOTE ON POLYRADIATE CESTODES 



The issue of Science for February 4, 1916, 

 N\ S., Vol. 43, No. 1101, page 170, contains a 

 note by Professor Barker referring to my 

 article on " Polyradiate Cestodes " published 

 in the Journal of Parasitology, September, 

 1915, calling attention to the omission of his 

 previously reported cases of triradiate speci- 

 mens of Taenia piriformis and T. serialis, and 

 to my error in considering that the case of 

 triradiate T. pisiformis which I reported was 

 the first on record. This is a valid criticism 

 and it is regrettable that Professor Barker's 

 paper should have been overlooked. None of 

 the other criticisms made by Professor Barker, 

 however, seems justifiable. 



In the first place, in regard to the specific 

 identification of the parasite, it has been my 

 experience in the course of several years, dur- 

 ing which time a large number of specimens 

 of dog tapeworms have been examined, that 

 Taenia pisiformis may be readily determined 

 upon the basis of the gravid segments alone. 



As to the other criticisms made by Professor 

 Barker, although I attach much less impor- 

 tance to the results of the feeding experiments 

 which I carried out than Professor Barker ap- 

 parently supposes (for the reason that the re- 

 sults of a single experiment of that kind are 

 of no great value as a rule, except when supple- 

 mented by the results of other experiments) it 

 seems proper to discuss briefly certain points 

 in my paper which appear to have been mis- 

 interpreted by Professor Barker. 



With reference to using, in feeding experi- 

 ments, material which had been in formalin for 



a few days, it was noted in my article that the 

 use of such material on several other occasions 

 had always resulted in the infestation of the 

 experiment animals. In fact it has been found 

 by repeated experience by myself and others in 

 this laboratory, that the ova of T. pisiforis 

 are extremely resistant to the action of for- 

 malin. Rabbits fed segments of T. pisiformis 

 which have been kept a few days in a solution 

 of formalin, not infrequently die shortly after- 

 wards and on postmortem examination show a 

 massive invasion of the liver with the early 

 larval stage of the parasite. 



It is a well-known fact that in the case of 

 several species of parasites, the ova of which 

 are characterized by a relatively thick egg 

 shell, the eggs are affected but little if at all 

 by formalin solutions. Ascarid eggs for ex- 

 ample may be kept alive for months or even 

 years, in formalin. Morris 1 when examining 

 some human feces which contained many eggs 

 of Ascaris lumoricoides and which had been 

 preserved in a 2 per cent, solution of formalin 

 for two years, found that some of the eggs 

 contained actively motile embryos. Four 

 months later there was an apparent increase in 

 the number of eggs containing embryos. In 

 my own experience it has been found that a 

 formalin solution is a very satisfactory medium 

 in which to incubate ascarid eggs, as it pre- 

 vents the growth of molds, bacteria, etc., with- 

 out interfering with the development of the 

 embryos. Various other substances commonly 

 destructive to protoplasm have been found not 

 to interfere with the development of ascarid 

 eggs. Leuckart 2 notes that the eggs of Ascaris 

 mystax may reach complete development in 

 alcohol, chromic acid and turpentine, while 

 Bataillon 3 has had ova of Ascaris megalo- 

 cephala showing living embryos after having 

 been for six months in Flemming's solution. 

 The latter also finds that the embryos in the eggs 

 remain intact and active in 50 per cent, alco- 



i Johns Hopkins Hospital Bulletin, Vol. 22, 

 August,- 1911, pp. 299-300. 



2 ' ' Die mensehlichen Parasitem, ' ' Vol. 2, 1 

 Lief., 1867, p. 212. 



3 Arch. Entwickelungsmech., Vol. 2, 1901, p. 

 149. 



