244 
Miscellanea 
VI. The Inheritance of Fertility. 
By R. E. LLOYD, D.Sc. (Lond.), Professor of Biology, Medical College, Calcutta. 
In a recent number of Biometrika Professor Pearson has criticised a short paper of mine 
which dealt with the fertility of rats*. This paper was in the main a record of observations 
which I knew to be accurate. No new principle was deduced by me from these observations, 
but I pointed out that they were opposed to a certain principle which had been enunciated by 
Professor Pearson and was now occupying a prominent position in a well known text-book. 
I mention this here since in summing up his criticism of my work and that of others Professor 
Pearson writes — "These are far from the only cases in which principles bearing on Evolution 
have been propounded on the basis of researches which prove in fact their negation." I do not 
understand this passage in reference to my own paper. I propounded no principle bearing on 
Evolution or any other subject, I merely opposed a principle which had been propounded by 
another. 
Professor Pearson has justly shown that I overlooked or at any rate did not point out that 
there was a very sensible relation between the weight of a rat and the number of its offspring. 
From my figures he demonstrates clearly that on the average large rats are slightly more fertile 
than small ones. He also points out that this fact is appreciable in my tables even before they 
have received mathematical treatment. This is undoubtedly true. 
On first reading the criticism, I thought that those who might read it without reference to 
the matter criticised, would receive the impression that I had written wholly in order to show 
that there was no correlation between weight and fertility in rats and that upon this 
demonstration I had set up some biological principle which was hardly worth mentioning. 
The impression that my paper would appear in this light was confirmed by an abstract of 
the criticism which has just been published in the following words, — "Lloyd has maintained 
that there is no correlation between size and fertility in rats, but it is shown that his tables 
indicate quite sensible correlation." — I sasv therefore that the main theme of my paper had 
become obscured owing to, Professor Pearson's critical treatment of what I regard as a side 
issue. 
The principle enunciated by Professor Pearson which was the subject of my remarks, is as 
follows — " Fertility is not uniformly distributed among all individuals but for stable races there 
is a strong tendency for the character of maximum fertility to become one with the character 
which is the type." I pointed out that my figures did not support this principle. My words 
are (A) " The maximum fertility of rats as measured by the number of young which they produce 
at a birth is not one with the character which is the type, as regards size " and again later on 
I say (B) " There is clear evidence that the la.rgest and the smallest rats are quite as fertile as 
those of average size." Professor Pearson chooses the second sentence for criticism and shows 
that it contains an untruth, but surely it must be obvious to anyone reading my paper that its 
main theme is concentrated in the first sentence (A). In speaking of the relation between 
weight and fertility Professor Pearson says — " But it is not a relation in which the type rat is 
the most fertile." This was my view precisely, it was indeed the chief view expressed in my 
paper. I cannot therefore admit that there is justice in Professor Pearson's remark — "It will be 
seen at once that Captain Lloyd's view is not supported by his own data." By inspection of the 
table I concluded that rats of normal size were not the most fertile. Professor Pearson came to 
the same conclusion and further pointed out that large rats were slightly more fertile than small 
ones. 
* Records Indian Museum, Vol. m. Pt. in. 
