Ned T Uke 
573 
THURSDAY, OCTOBER 9, 1902. 
MENDEL’S THEORY OF HEREDITY. 
Mendel’s Principles af Heredity: a Defence. By W. 
Bateson, M.A., F.R.S. Witha Translation of Mendel’s 
Original Papers on Hybridisation. Pp. xiv + 212. 
(Cambridge : University Press, 1902.) Price 4s. net. 
Reports to the Evolution Committee of the Royal Society. 
Report I. Experiments undertaken by W. Bateson, 
F.R.S.,and Miss E. R. Saunders. Pp. 160. (London: 
Harrison, 1902.) Price ros. 
HERE can be no question of the importance, in refer- 
ence to evolutionary theory, of a proper comprehen- 
sion of the principles of heredity. Many attempts towards 
a solution of the problem have been made, but to none of 
them has it been possible hitherto to give more than a 
provisional approval. While the nature of this process 
remains unknown, the fabric of evolution cannot be 
regarded as in any sense complete. It seems certain 
that at present the question may be most hopefully 
approached from the statistical side, and to the labours 
of Galton and of Pearson we owe the enunciation of a 
law which gives quantitative expression to many of the 
observed facts. But about two years ago the discovery 
was made that Gregor Mendel, sometime Abbot of 
Briinn, had long since, in the seclusion of his cloister, 
devised and carried through a very remarkable series of 
experiments in cross-fertilisation ; and had on them based 
a theory which bids fair, if its truth can be established, 
to put the whole subject of heredity on an entirely new 
footing. 
After more than thirty years of neglect, the Mendelian 
theory has found an energetic champion in Mr. Bateson, 
to whose lucid and exhaustive exposition of the doctrine 
in the two volumes before us students of the problem 
will naturally turn. Here we can only state in very 
briefest outline some of the main cenclusions to which 
Mendel was led. In the instances (of pea-plants) 
selected by him for experiment, it was found that 
when two plants, differing in a given feature, were 
crossed, the hybrid offspring invariably exhibited one 
of the parental characters (called by Mendel the 
“dominant”) to the entire or partial exclusion of the 
other (called “recessive”). After self-fertilisation, each 
hybrid produced offspring in which the two antagonistic 
parental characters (Bateson’s “ allelomorphs”), dominant 
and recessive, appeared in a ratio closely approximating 
on an average to 3:1. Further experiment showed that 
while the recessive minority henceforth bred true, the 
other class consisted of one-third genuine dominants 
also breeding true, and two-thirds “ cross-breds ” (Bate- 
son’s “heterozygotes ”), which latter on self-fertilisation 
again gave the old ratio of 3:1, and so on. When 
plants differing in several characters instead of one only 
were taken, mutatis mutandis the same law was found 
to hold good. From these and other experiments, in- 
geniously devised and giving wonderfully accordant 
results, Mendel was led to formulate the hypothesis of 
the numerical equality in kinds, and purity in respect of 
given characters, of the gametes produced by any 
zygote, whatever the composition of the latter. The 
NO. 1719, VOL. 66] 
consequences of the acceptance of this view would un- 
doubtedly be far-reaching, and Mr. Bateson does well, in 
reprinting a translation of Mendel’s original papers and 
also in recording the illustrative experiments made by 
himself and Miss E. R. Saunders, to trace out in 
considerable detail the main lines of speculation thus 
laid open. 
The chief issue between the Mendelian and Galtonian 
conceptions is the question of “ ancestral” heredity ; and 
in disallowing the latter Mr. Bateson is pitting himself 
against a formidable triumvirate. Prof. Weldon has 
discussed Mendel’s results from this point of view in a 
critical, but, as it seems tous, not unfriendly spirit. Much 
may be conceded to the zeal of an advocate, but we regret 
certain personalities in Mr. Bateson’s ‘‘ Defence.” An 
impartial judge, after hearing the able statements of 
counsel, would probably desire to adjourn the case for 
the production of further evidence. 
On p. 71 of the first-named work, Aéaé should read 
Ab+ab, and similarly eBad should be aB+ad.  Giltay’s 
name appears in the bibliography as “ Gitay.” 
F. A. D. 
LIGHTNING ARRESTORS IN ELECTRICAL 
ENGINEERING. 
Die Schutzvorrichtungen der Starkstromtechnik geger 
atmosphariscthe Entladungen. By Dr. Gustav 
Benischke. (Brunswick: Friedr. Vieweg und Sohn.) 
ie is customary in Germany to divide electrical 
engineering into two parts, the “ Starkstrom” and 
‘*Schwachstrom ”—the “strong” and “‘weak” current 
branches. This book is the first issue of a series, 
edited by Dr. Benischke, each issue to be complete in 
itself and to deal with some application of the industry. 
The first issue treats of the means adopted in the 
“strong current” branch, z.e. electric lighting and power, 
for protection against atmospheric electrical discharges 
With overhead lines, especially overhead power-trans- 
mission lines, this subject is one of great importance,, 
and is also one upon which very little is known with 
certainty. It is interesting to find that the author, on the 
first page, gives it as his opinion that it is impossible to. 
protect a line against the effects of being directly struck 
by lightning. In such a case a destruction of the in- 
sulation is bound to take place. It is well that electrical 
engineers should understand this, and be clear in their 
own minds that the so-called lightning arrestors at pre- 
sent on the market afford no protection here. Fortunately, 
such cases are very rare. Protection is afforded, accord- 
ing to Dr. Benischke, by lightning arrestors against the 
weaker side discharges which accompany the main 
lightning flash, also against spark discharges due to the 
static charges which the overhead conductors assume as 
the result of dust, snow, &c., and against induced dis- 
charges caused by atmospheric electrical disturbances in 
the neighbourhood. 
The book contains a very clear and concise description 
of the various forms of lightning arrestors at present in 
use. Nearly all of them consist of spark gaps placed 
with one side of the gap connected to the conductor and 
the other side to earth. Should, therefore, at any time 
the conductor become charged to a high potential, a 
BB 
