526 



SCIENCE 



[N. S. Vol. XXXVII. No. 953 



size, the nuclei showed displacement and as 

 regards the Nissl granules there was a condi- 

 tion of chromatolysis or achromatosis more 

 or less complete. When the serum or cerebro- 

 spinal liquid from one of these animals was 

 injected into the fourth ventricle of a normal 

 dog this latter animal in a short time gave 

 evidence of somnolence, more or less marked, 

 and upon histological examination showed in 

 the cerebral cortex degenerative changes of 

 the same character as those described for the 

 animal suffering from insomnia. On the basis 

 of these and similar observations the author 

 believes that he has demonstrated the forma- 

 tion during the waking condition of a toxin 

 which may be supposed to have a direct effect 

 in the production of natural sleep. As it 

 accumulates it provokes a condition of fatigue 

 or diminished irritability in the sensory-motor 

 apparatus of the central nervous system, which 

 under the usual conditions may pass into 

 normal sleep. In cases of prolonged insomnia 

 the greater accumulation of the toxine may 

 lead to the production of distinct lesions in 

 the cortical cells and finally to death. When 

 the author comes to apply this idea to an ex- 

 planation of the mechanism of the daily sleep 

 he encounters a number of theoretical objec- 

 tions which are enumerated and discussed 

 with commendable frankness. The fact that 

 seems to him to be the most difBcult to har- 

 monize with his theory is the abruptness with 

 which sleep may appear and disappear. On 

 his view of a gradual intoxication of the nerve 

 cells he admits that there should be a pro- 

 gressive development of somnolence as the tox- 

 ine gradually depresses the activity of the 

 nerve cells. In view of this difficulty he feels 

 obliged to call upon a secondary hypothesis, 

 suggested by the general views of Brown- 

 Sequard, according to which the hypnotoxine 

 under usual conditions does not paralyze or 

 inhibit the cortical cells directly, but exerts 

 its action indirectly by putting into play an 

 inhibitory nervous mechanism of unknown 

 nature which suspends reflexly the activity of 

 the cells. The reader who follows the au- 

 thor's presentation of the positive results of 



his experiments, with an increasing conviction 

 that here at last has been discovered a defi- 

 nite factor destined to throw light upon the 

 causation of this mysterious daily rhythm, is 

 conscious of a distinct feeling of disappoint- 

 ment when he is asked to accept this unat- 

 tractive hypothesis of an intermediary inhibi- 

 tory apparatus. One can only conclude that 

 the author has made another addition to the 

 long list of unsatisfactory theories of sleep. 

 However, we must feel grateful to M. Pieron 

 for an apparently very reliable presentation 

 of the difficult literature of the subject, and 

 for the experimental results which indicate 

 that during insomnia a definite toxic material 

 is formed in the body. It is to be hoped that 

 his findings in regard to this hypnotoxine will 

 be corroborated and extended by other ob- 

 servers, although it must be confessed that the 

 experimental procedure involved in the pro- 

 duction of long-continued insomnia is of such 

 a character that few investigators are likely tO' 

 be attracted to the work. 



W. H. Howell 



The Mosquitoes of North and Central Amer- 

 ica and the West Indies. By Leland O, 

 Howard, Harrison G. Dyar and Frederick 

 Knab. Volumes 1 and 2. Washington, 

 D. C, Carnegie Institution. 1912. Pub- 

 lished January and February, 1913. 

 Nearly thirty years ago I heard Cobbold, 

 the well-known authority on parasitism, lec- 

 ture on Filaria sanguinis-hominis and its re- 

 lation to the mosquito. It was a good lec- 

 ture, and created a profound impression; but 

 we who discussed the marvel at that time 

 little imagined what still remained hidden be- 

 hind the curtain, the merest corner of which 

 had been lifted. In those days the Culicidae, 

 whether regarded from the medical or ento- 

 mological point of view, were supposed to be 

 relatively unimportant. To-day it seems as- 

 tonishing that we could have been so igno- 

 rant, and yet all the work that has been done 

 is very far from exhausting the subject. In 

 April, 1902, Dr. L. O. Howard applied to the 

 Carnegie Institution of Washington for a 

 grant " which should enable the preparation 



