132 
But while we may well be grateful to the writer 
who has tried in this little book to make a very 
difficult subject somewhat less difficult, it must be 
confessed that the book is too condensed, too 
strenuously logical, and, moreover, too much 
occupied by questions of priority, to attract the 
general scientific reader, or, indeed, any but the 
professed student of its own subject. Prof. Roux 
has greater powers than are put in action here. 
Haeckel’s ‘‘Generelle Morphologie” is now prac- 
tically obsolete ; but it marks an epoch in biologi- 
cal science, and it stands as a monument of clear 
thinking and lucid scientific expression. Let us 
hope that some day or other Prof. Roux will give 
us not only a vocabulary, not only isolated re- 
searches, however important, but will crown his 
labours by the writing of a newer and a better 
“Generelle Morphogenie.” Dr SWweed: 
RUBBER AND RUBBER PLANTING. 
Rubber and Rubber Planting. By Dr. R. H. 
Lock. Pp. xilit+t245+x plates. (Cambridge: 
Wniversity ress. 1903.) \Price s.,net. 
R. R. H. LOCK was connected, until re- 
cently, with the Botanic Department at 
Peradeniya, Ceylon. In conjunction with other 
officers of that department, he conducted a series 
of very valuable experiments in connection with 
the tapping of rubber trees. 
The book before us contains much that has 
already been published by the author officially in 
Ceylon. The diagrams and photographs illus- 
trate many interesting features in connection with 
Hevea, Manihot, Castilloa, Funtumia, Ficus, and 
Landolphia, such as is rarely found in a book 
on rubber. 
The book deals with the botanical sources and 
history of rubber, physiology of latex, the usual 
planting and harvesting operations, and the vari- 
ous pests and diseases of rubber plants. Each 
chapter is written in a very easy and popular style, 
and the subject-matter can be easily understood 
by the general reader. 
The special line of work in the book is that 
which relates to tapping operations. When deal- 
ing with the effects of wounding the bark, the 
author lays stress upon the fact that any system 
of tapping which involves the cutting of the whole 
circumference of the tree at one time is bad. 
He suggests that in no circumstances should more 
than one-half of the total circumference of the 
tree be tapped at one time. 
The yield of rubber bears a peculiar relation to 
the volume of bark on the tree. An instance is 
quoted of one tree which in three years yielded 
240 lb. of dry rubber; the rubber was contained 
NO. 2319, VOL. 93| 
NATURE 
[APRIL 9, 1914 
in 70 gallons of latex, equivalent to 20,000 cubic 
inches. This yield of 20,000 cubic inches of latex 
was obtained by tapping an area of bark which 
had contained only 500 cubic inches of latex at 
the beginning of the experiment. The problem, 
therefore, resolves itself into one of the origin 
of the balance of 19,500 cubic inches of latex. 
| The author concludes that the greater part of 
the latex can only have been produced by secre- 
tion of latex in the existing laticiferous tissue, 
thus suggesting that the latter is an organ for the 
actual manufacture, as well as storage, of the 
milky liquid. 
It is common knowledge among experimenters 
in the tropics that the yielding capacity of rubber 
trees exhibits enormous variation. It is this varia- 
tion which renders the majority of the public 
records of experiments valueless. Dr. Lock 
shows in certain experiments that the highest and 
lowest average yields for particular operations 
were respectively 106 and 8 cubic centimetres. 
The yield per unit of bark removed was in the 
ratio of 317 to 25—a variation of 1,000 per cent. 
in yields from trees which to the author appeared 
to be somewhat similar. In addition to this varia- 
tion in yield, there is an equally marked variability 
in composition of the latex according to frequency 
of tapping, season of tapping, altitude, and so 
forth. 
In the middle-East, the majority of planters tap 
the same area on the same day, or on alternate 
days, the intervals between successive tapping 
operations being regarded as sufficient to enable 
the latex to accumulate to the desired quantity 
and degree of concentration. Dr. Lock is prob- 
ably the first experimenter who has continued ex- 
periments for a period of four years, and herein 
lies the great value of his work. The majority of 
tapping experiments have usually lasted a number 
of months, and on that account alone are apt to 
be highly misleading. 
Dr. Lock concludes that, after 34 years’ con- 
tinuous tapping, the yield from trees tapped once 
a week may become as great or greater than that 
from trees tapped at any shorter interval. It was 
this conclusion which gave rise to a controversy 
in the columns of the India-rubber Journal, which 
in turn led the Rubber Growers’ Association in 
London to take up experimental tapping on various 
Eastern estates. Later publications from Malaya 
do not agree with the result obtained from Dr. 
Lock in Ceylon, but this might very well be due 
to the fact that the experiments in Malaya have 
not been continued for the same period of time. 
Altogether, the book can be regarded as being 
of great value, not only to the practical man on 
the estate, but also to investigators in this country. 
Hee W. 
ee a 
