NATURE 



[September 8, 1910 



Sir Christopher Wren may have known from travellers 

 or by converse with foreign men of science of this example, 

 but it is not necessary to jump to that conclusion, as an 

 ordinary brick kiln or oast house would give the idea, 

 aided by Wren's mathematical analysis of cones as units 

 of high carrying power. 



Taylor and Cresy's drawings of the Pisan monuments 

 have every appearance of being most trustworthy, and 

 should be consulted by your correspondent. I had the 

 plates with me when visiting Pisa in 1890, and I had the 

 opportunity to go up the tower and round its galleries. 

 Ruskin has a passage on the setting out of the lower part 

 of the western facade of the cathedral, but I remember 

 the impression produced by my examination was not 

 favourable to his argument. 



.'\rthur T. Bolton. 



Victoria Mansions, 28 Victoria Street, 

 Westminster, S.W. 



The Origin of the Domestic " Blotched " Tabby Cat. 



The question of the origin of the tv/o types of our 

 domestic cats has been the subject of much controversy, 

 and it is therefore with diffidence that the views here ex- 

 pressed are now put forward. It is, of course, well known 

 that any domestic " tabby " can, at a glance, be assigned 

 to one of the two colour patterns, " striped " or 

 " blotched." 



In a recent paper (Proc. Zool. Soc, 1907, pp. 143-66) 

 Mr. R. I. Pocock comes to the conclusion that the origin 

 of V. catus (blotched tabby) is " at present quite un- 

 known," and suggests that it is "the survivor of some 

 extinct, probably Pleistocene, cat of Western Europe " 

 {ibid., p. 160); in effect, he regards catus as a good 

 species. It seems to have been pretty clearly shown by 

 the same writer that the torquata breed (striped tabby) is 

 either the direct descendant of F. sylveslris or is the result 

 of a cross between that species and F. ocreata (Proc. Zool. 

 Soc, 1907, p. 947, and Nature, vol. Ixxvii., p. 414), which 

 latter is, no doubt, merely a geographical race of sylvestris. 



In his previous paper (Proc. Zool. Soc., 1907, p. 160) 

 Mr. Pocock remarks that " when two distinct species cross 

 the hybrid sometimes reverts in some respects to the 

 characters of a [supposed] common ancestor of both"; 

 this cannot be denied, but such a cross more commonly 

 results in a form intermediate between the two parents, 

 usually designated as a mongrel. After much diligent 

 search, I have been unable to find a single instance in 

 which complete segregation has taken place in respect of 

 all specific characters when two well-defined species are 

 crossed. 



The two " types " of tabby, when crossed, always pro- 

 duce individuals which are at once referable to one or the 

 other variety ; in short, we get complete (Mendelian) 

 segregation in respect of this character. 



■ It therefore seems to me to be incompatible with the 

 above observed facts, that F. catus is the survivor of some 

 extinct cat of Western Europe, for if catus were a good 

 species, when crossed with torquata we would most 

 certainly have some form of intermediate produced. This, 

 as we know from everyday experience, is contrary to the 

 expressed results of such a cross. From these facts it is 

 suggested as a possible explanation that F. catus arose 

 per saltum from F. sylvestris. In short, I believe that 

 F. catus has arisen from F. sylvestris as a " sport," and 

 when crossed with its parent species or inter se follows 

 llie Mendelian law of segregation, as many such discon- 

 tinuous variations have now been proved to do. At the 

 same time (from evidence which cannot be here brought 

 forward), it would appear that only in extremely rare 

 rases, if at all, can Mendelian action be accountable for 

 the evolution of a species in nature. 



In opposition to such an origin, Mr. Pocock urges 

 (Proc. Zool. Soc, 1907, p. 160) " the complete absence 

 of evidence that species of Felis are ever dimorphic in 

 pattern, and the ascertained fact that they breed true to 

 their specific and sub-specific type." The objection, of 

 course, is a purely negative one, and there is some evidence 

 to show that animals under domestication are more subject 

 to pronounced variation than in a state of nature. 



In the leopard (f. pardu.'i) we have a species of felis 



NO. 2132, VOL. 84"! 



which can most certainly be regarded as dimorphic, inj 

 that it produces a black form, and (so far as the some- 

 what meagre information on the subject goes) in its- 

 gametic behaviour is exactly comparable to the case of 

 the " blotched " and " striped " tabby. There are, so far 

 as I know, no data in the case to show which is the 

 " dominant " form, but, from analogy, it is almost certain 

 the black would be dominant over the spotted. It is 

 the hope of obtaining such information in the case of our 

 common cats which has induced me to approach the sub- 

 ject. Finally, it may be said that, although no direct 

 proof can be brought forward in support of such a sugges- 

 tion, I am convinced that a properly conducted series of 

 experiments with the two types would bring to light much 

 evidence in favour of such a view. 



Unfortunately, the writer is at present unable to carry 

 out such a series of experiments, and it is hoped that 

 i others may hereby be induced to do so. 



H. M. ViCKERS. 



81A Princes Street, Edinburgh, .\ugust 20. 



I AM glad Mr. Vickers has directed the attention: 

 of MendeUans to the question of our two types of " tabby " 

 cat. With the same purpose in view, and in the hope of 

 inducing someone with time and facilities at his disposal 

 to carry out breeding experiments with these animals, I 

 recently communicated to the Mendel Society a paper on 

 this subject, which will appear in the forthcoming issue 

 of the journal. The results of such experiments are sure 

 to be interesting, but whether or not they will settle the- 

 origin of the " blotched " tabby is another matter. They 

 may turn the balance of the evidence in favour of this or 

 that theory, but it is doubtful if they will result in more 

 than a hypothetical conclusion. For myself I have quite 

 an open mind on the point. As stated in my original paper 

 on English cats, the " blotched " tabby may be regarded 

 provisionally either as a survivor of some e.xtinct cat that 

 "formerly inhabited Europe or as a " mutation " of the 

 " striped " tabby. I reserved the names " catus " and 

 " torquata " for these two types as a convenient means 

 of designating them, following Linna;us's method, which 

 is still in vogue, of assigning a specific epithet to our 

 domesticated animals, like Ovis aries, Canis familiarise 

 and others, when their origin is uncertain or unknown. 



I think Mr. ^'ickers a little overstates the case when- 

 he says there has been much controversy on the subject 

 of the origin of these cats, and speaks of their existence 

 as well known. It was the fact that the remarkable 

 differences between them had been practically ignored or 

 unappreciated by zoologists that induced me to discuss the 

 question at some length three years ago. Nor do I think 

 Mr. Vicker?. himself quite appreciates the distinction I 

 emphasised between dimorphism in pattern and dimorphism 

 in colour. E.xperience with wild animals shows that 

 pattern is far more stable than colour. Pattern is wonder- 

 fully persistent ; colour is not. No one would be greatly 

 surprised at finding a black or white example irT a litter 

 of spotted hyasnas, but it would be admittedly an 

 extremelv remarkable thing if a specimen resembling a 

 striped hya;na in pattern occurred amongst them. .Such 

 a " mutation " would be comparable to the " mutation," 

 if mutation it be, of the " blotched " from the " striped " 

 t.abbv cat. Such a mutation in pattern as that supposed 

 in the case of the hy;Ena may, of course, be produced 

 to-morrow ; but, so far as I am aware, no such variation 

 has as yet been recorded, and I write this with full recol- 

 lection of the curious variations in pattern that have been 

 recorded of the common leopard. 



Finally, may I demur to one more statement made by 

 Mr. Vickers, namely, that animals under domestication 

 are more subject to pronounced variation than those in a 

 state of nature? I do not dispute this common assump- 

 tion, but I am not satisfied that the evidence in its favour 

 amounts to very much. 



The questions raised by Mr. Vickers are, however, full 

 of interest ; and all that I have said is in justification of 

 the agnostic attitude that I think should be, for the pre- 

 sent, preserved towards the origin of the " blotched " 

 tabby cat. R. I. PococK. 



Zoological Gardens, .\ugust 24. 



