ete 
NALROTE 
[ Marcu 28, 1907 
of ticks found on diseased animals that transmitted the in- 
fection. The transmission is thus hereditary, and of a 
transmission of this kind we have no evidence at all in 
the case of malaria, though it has been stated that this 
mode of transmission occurs in yellow fever. 
The transmission of Piroplasma by ticks is thus peculiar, 
and when we come to examine the known facts closely the 
peculiarity increases. Smith and Kilborne, as we have 
stated, showed that the infection of Texas fever due to 
P. bigeminum. was carried by ticks in their larval stage. 
In the case of P. canis producing malignant jaundice in 
dogs the mode is different. In this case it is not the 
larva, but the adult tick of the second generation that 
transmits the disease. This also is the case for red-water 
of sheep due to P. ovis. In the case of piroplasmosis of 
the horse, the mode has not yet been definitely established. 
Finally, in the case of ‘‘ African coast fever ’’ in cattle, a 
disease resembling in some respects ‘‘ Texas ’’ fever, but 
due to a different Piroplasma, viz. P. parvum, we appear 
to have a still more complex state of things. The trans- 
mission, according to Lounsbury, in the case of the tick 
(R. appendiculatus) is not hereditary, but is transmitted 
by nymphs which in the larval stage have fed on infected 
animals, and.also by adults which in the nymphal stage 
have fed on infected animals. Hence it is clear that 
analogy as a guide is almost useless, and it must be deter- 
mined by actual experiment how in each case the trans- 
mission is brought about. Of the actual changes under- 
gone by the Piroplasma in the tick,,egg, larva, nymph, as 
the case may be, we know but little. 
Recently, however, Koch described peculiar forms in the 
stomach of the tick which he considers to represent a 
cycle of development. Other forms have also been found in 
the egg, but not, so far, in the larva or nymph. No doubt 
research will be in the future directed to these points. 
Piroplasmosis is, then, an important set of diseases trans- 
mitted by ‘ticks, but, further, they have been recently 
shown to play a part in the transmission of those minute, 
slender, corkscrew-like parasites known as_ Spirochztes. 
These parasites give rise in man to a dangerous and often 
fatal fever, a marked character of which is the tendency 
to relapse. Hence it is known as recurrent or relapsing 
fever. The cause of relapsing fever has been long known 
to be a Spirochete, viz. S. obermeteri, but it is only 
recently that the nature of ‘* African tick fever ’’ has been 
elucidated. This is also due to a Spirochete, and as it 
is different from the former it has been named S. duttont, 
after the late Dr. Dutton, who with Todd was the first 
to elucidate the mode of transmission of the disease. The 
memoir of the Liverpool School of Tropical Medicine con- 
tains an elaborate study, clinical and experimental, of the 
characters of this Spirochete. Perhaps the most convincing 
proof brought that these two Spirochzetes are different 
lies in the fact that an animal that has recovered from an 
attack of the one is still susceptible to inoculation with 
the other, and vice versd. How the ordinary relapsing 
fever is transmitted is still uncertain; it may be by bugs, 
though the numerous experiments recorded in this memoir 
to transmit S. duttoni in this way have all failed; but ticks 
are the transmitters of S. duttoni, and in Africa the par- 
ticular tick implicated is Ornithodoros moubata (Murray). 
This tick, long of evil reputation, can transmit the disease 
in the following ways:—(r1) directly, i.e. by means of 
adults that have sucked the blood of infected patients ; 
and (2) by the nymphal descendants of these adults. 
Spirocheetes have also been found by Koch in the eggs of 
ticks, but whether or no they undergo any development is 
at present unknown. 
From what we have said it will be evident that to the 
medical man a knowledge of ticks is of the utmost import- 
ance, and every medical man will welcome this memoir 
of Captain Christophers on the anatomy and histology of 
ticks. The histological portion will be especially useful, as 
the systematic treatises, e.g. Neumann’s memoirs, deal 
solely with the external characters on which their classifi- 
cation is founded. The internal anatomy of ticks has until 
quite recently been described in a very meagre fashion, 
and it is evident that such a knowledge is absolutely neces- 
sary in the search for developmental forms of Piroplasma 
and Spirochzeta in the various tissues. 
Those who are acquainted with Captain Christophers’s 
NO. 1952, VOL. 75] 
previous work on the anatomy and histology of the mos- 
quito will know what to expect in this memoir. 
The clear descriptions, illustrated by numerous diagrams 
and six photogravure plates, might with advantage be 
imitated by other recent writers on the same subject. 
With regard to the plates, unfortunately in passing 
through the press the lettering of many of the figures has 
not appeared. We may note also that the secretion from 
the coxal glands was observed by Dutton and Todd in the 
Congo. 
The Liverpool memoir, besides the study of S. duttont, 
contains a description of various attempts made to cultivate 
this Spirochzte, but all in vain. A new Spirochete in the 
mouse, S. laverant, is also described. Two papers on 
Trypanosomes, and a number of pictures of the research 
laboratories at Runcorn of the Liverpool Tropical School, 
complete a very interesting memoir. 
J. W. W. STEPHENS. 
TROPICAL BOTANY. 
AN interesting number of the Annals of the Royal 
Botanic Gardens, Peradeniya (London: Dulau and 
Co.), has just appeared. In the first paper Mr. R. H. 
Lock gives the third instalment of his work on_plant- 
breeding in the tropics, dealing with maize. Unlike some 
Mendelian experiments, the results have been obtained 
with large numbers, and on a total, for instance, of 111,697 
seeds, the result was 50-17 against an expectation of 50-11. 
The second paper is by Mr. T. Petch, on the fungi of 
the nests of the common termites, or white ants, of Ceylon, 
a worthy successor of Moller’s classical paper on the fungi 
of the leaf-cutting ants of South America. He has worked 
out in detail the entire life-histories of the fungi, and 
shows that while the ‘ regular’’ fungus is a Volvaria 
(already described elsewhere, as are so many of the tropical 
fungi that have only been worked at in Europe, under at 
least six genera), the garden also contains ‘‘ weeds,’’ one 
of which, at least, a Xylaria, is impossible of eradication 
by the ants. Incidentally, grave doubt is thrown on 
Moller’s theory of selection of the fungus by the ants, for 
the ‘‘ Kohl-rabi heads’’ occur in the termite nests in an 
even more perfect and complex form than in the leaf- 
cutters’ nests, and yet the same form appears on an allied 
outside fungus not cultivated by the ants. The paper is 
well illustrated. 
The third paper is by Dr. Willis, on the flora of Ritigala. 
This is an isolated mountain in the *‘ dry ’’ zone of Ceylon, 
forty miles from any other, and high enough to condense 
much moisture on the top, where are found 103 species 
not otherwise known in the dry zone. These, being species 
of the lower zone of the southern mountains, must have 
leapt the whole forty miles in one operation. Among 
them are twenty-four bird-carried things, with one very 
slightly marked endemic variety among them; forty-nine 
wind-carried things (including twenty-four ferns), with two 
endemic species and one variety; and thirty plants the 
mode of distribution of which may be called doubtful or 
accidental. Six of these are low-country plants which 
might come by easy stages, and of the remaining twenty- 
four no less than nine are endemic to Ceylon and to the 
couple of acres of the summit of Ritigala. One of these 
nine has been found in South India, but the other eight 
are confined to Ritigala. This goes to show, therefore, 
thal endemism goes with difficulty of distribution and rare 
arrival in one spot. 
Tie final paper is by Mr. A. M. Smith, who has followed 
up Blackman’s already almost classical paper on optima 
and limiting factors by a careful study of growth under 
different conditions in Ceylon—where it is rapid, and can 
be easily measured—and finds that Blackman’s theory ex- 
plains matters well. In Dendrocalamus (giant bamboo) at 
Peradeniya the limiting factor is humidity, while at night 
at Hakgala, where it is cold, the temperature is limiting 
and humidity has no effect. This work explains, but 
renders practically valueless, the enormous mass of observ- 
ations on growth made by physiologists from Sachs on- 
wards, and no one interested in physiology can afford to 
leave this paper unread. It also helps to show what an 
opening there is for really good physiological work in the 
tropics. The whole number is one of considerable interest 
and importance, and cannot be neglected by botanists. 
