July 15, 1909] 



NA TURE 



/o 



ito the botany of each district, but a general sketch of 

 the distribution of the flowering plants, at any rate, 

 should have been given in this " Guide." The island 

 would afford excellent scope for a botanical survey, on 

 the lines of the well-known work done by Dr. Smith, 

 Dr. Moss, and other ecologists, in various parts of 

 Britain. It is greatly to be hoped that in a future 

 edition of, or supplement to, this " Guide " it will be 

 found possible to include a chapter on plant distribu- 

 tion, with a veg'etation map of the island, and, for 

 ■comparison and correlation, a geological map. This 

 would, if carefully done, preferably by an ecologically- 

 minded, botanist residing in the district, undoubtedly 

 enhance the value of the book and secure for it more 

 than the local interest that attaches to a merely 

 fioristic work. 



l'lwto.\ 



[//. F. Poole. 



Fig. 2. — White Stork — a rare visitor — captured at Shorwell in 1902. From 

 " A Guide to the Natural History of the Isle of Wight," 



The second suggestion we venture to make, with 

 reference generally to books similar in scope to this 

 " Guide," is that most of the systematists responsible 

 for the various lists of plants and animals given in 

 local naturalistic compilations would do well to obtain 

 the cooperation of a biological botanist or zoologist 

 when writing their prefatory remarks on the group 

 of plants or animals they are dealing with. So far 

 as this " Guide " is concerned, we refer chiefly, as 

 examples, to the sections dealing with some of the 

 cryptogamic plants. It would be far better for the 

 average cryptogamic systematist to pass straight on 

 to his list and say nothing whatever about the life- 

 history and development of his group than to write a 



NO. 2072, VOL. 81] 



string of incoherent and inaccurate sentences, repeat- 

 ing and perpetuating long since exploded errors and 

 mare's-nests. Lichenologists, we know, are a stiff- 

 necked generation, but surely it is time they hesitated 

 to record in print their refusal to recognise the dual 

 nature of the lichen thallus, which has been fully and 

 finally established. There can be no excuse, either, for 

 the hepaticologist who tells us that the liverworts are 

 " linked to the lichens " by means of their thalloid 

 forms ! The account of the relationship between the 

 liverwort FruUania and the rotifer which sometimes 

 occupies its pitchers is entirely imaginative. The list 

 of hepatics (liverworts) is conspicuous by the omission 

 of several species which are certainly' found in the 

 island, and often abundantly in places,' such as Anlho- 

 ceros laevis, Scapania nemorosa, and Lepidozia 

 reptans. 



The articles by Mr. G. W. Colenutt (geology), Mr. 

 P. VVadham (fishes, mammals, &c.), and Mr. R. H. 

 Fox (birds) stand out as refreshing oases in the arid 

 desert of species lists, being written in a " nature- 

 study " spirit which can hardly be said to characterise 

 the work of the other contributors. The " Guide " is 

 illustrated by twenty-six excellent plates, chiefly from 

 photographs by Mr. H. F. Poole, two of which we are 

 permitted to reproduce here. F. C. 



SLEEPING SICKNESS."- 



IT may be taken as definitely established that sleep- 

 ing sickness is due to infection with a trypanosome 

 {Trypanosoma gambiensc), and that this trypanosome 

 is conveyed by a tsetse-fly (Glosshia palpalis). But if 

 we proceed to analyse and extend this proposition 

 we soon get into ditficulties. We do not know for 

 certain whether man is the only ." reservoir -" of this 

 trypanosome, or whether monkeys and other mammals, 

 especially native dogs-, can also harbour it. Should 

 this prove to be so — though the balance of evidence 

 is against the supposition — it must materially affect 

 prophylactic measures. If we consider next the mode 

 by which the trypanosome is conveyed we find our- 

 selves in the midst of the most conflicting evidence. 

 It is still uncertain whether the transmission is 

 mechanical or whether there is a cycle of development - 

 of the trypanosome in the fly ; facts appear to be all 

 in favour of the first view, analogy all in favour of 

 the latter. Nor is the question a purely academical 

 one, for if the transmission is mechanical, then the 

 flies are no longer infective after the infecting. reser- 

 voir (man) is removed ; if, however, there is a cycle 

 of development, then it remains to be determined how 

 long an infected fly can remain infective after the 

 infecting source is removed. 



If, again, we consider the question. Can sleeping 

 sickness be conveyed by any other species of tsetse- 

 fly than Gl. palpalis? we must confess our ignorance. 

 The balance of evidence certainly seems to be against 

 the possibility, but should it be shown that other 

 species can convey the disease, then the question of 

 prophylaxis would be even more difficult than it now 

 is. These reports show that these are some of the 

 questions that urgently need solution, but there are 

 others of equal importance which arise in the imme- 

 diate carrying out of prophylactic measures. They 

 concern the fly itself, its habits, duration of its life, 

 its breeding grounds, its food, its powers of flight, its 

 likes and dislikes in regard to foliage, trees, shrubs, 

 grass, &c. These questions are all important, and 



1 " Reports of the Sleeping Sickness Commission of the Royal Society." 

 No. ix. 



2 The existence of such a cycle is now practically established by the 

 recent work of KJeine confirmed by Bruce. 



