April 23, 1897.] 



SCIENCE. 



657 



are illusions of some sort. Their general char- 

 acter* is what would be shown if the adjusting 

 screws of an objective were set up too tightly, 

 producing a set of strains in the glass, or if the 

 objective were strained by its cell. Strains of 

 this sort will sometimes produce faint com- 

 panions to stars sufficiently bright. A com- 

 parison of all the drawings of Venus available 

 in the library of the Lick Observatory is very 

 instructive. All observers, except those at 

 Flagstaflf, see faint markings of one class, while 

 those drawn by Mr. Lowell are of a totally dif- 

 ferent nature. 



Venus has been observed on very many oc- 

 casions at Mt. Hamilton, with our essentially 

 perfect twelve-inch object-glass, in the years 

 1888-1897, without once seeing markings of the 

 kind drawn by Mr. Lowell, or ' distinct ' mark- 

 ings of any kind. Faint and indistinct mark- 

 ings, of the character of those drawn by scores 

 of observers for a century past, are, however, 

 seen when the circumstances are good. 



The foregoing notes seem to me to throw 

 doubt on the reality of the markings reported 

 from the Flagstaff Observatory. Until Mr. 

 Lowell's observations are fully comfirmed by 

 other observers with other telescopes, it will be 

 wise not to accept them unreservedly. 



Edward S. Holden. 



Mt. Hamilton, March 9, 1897. 



FURTHER CONSIDERATIONS ON THE SYSTEMATIC 

 POSITION OF TARSIUS. 



Professor Hubbecht has replied with some 

 warmth to the paper I lately published in 

 Science, in which I attempted to show that, 

 in my opinion, Tarsius is more of a lemur 

 than an ape, although in reality an annectant 

 type between the two. The objection I raised 

 to placing Tarsius among the apes and the 

 effect of this transferral on the classification 

 of the Primates based on their osteology re- 

 lated to recent forms. Professor Hubrecht is 

 probably quite aware that, when we introduce 

 the fossil Primates into the question of classify- 

 ing the recent forms, the apparently sharp 

 lines of demarcation between the skeletons of 

 recent lemurs and apes disappear. 



*Six or more radial rays, thicker at the outer rim 

 of the image of the planet. 



I entirely agree with Professor Hubrecht ini 

 the idea that classification should be based 

 as far as possible on phylogeny, and that the 

 only truly scientific arrangement of animals 

 depends upon a knowledge of their whole or- 

 ganization, both embryonic and adult. I claim, 

 however, that the paleontological method in 

 determining phylogeny is more nearly accurate 

 than the embryological, as in the latter many 

 characters are lost and innumerable caenogenetic 

 variations are introduced which the embryolo- 

 gists often cannot distinguish from real homo- 

 genetic structures. The great number of phy- 

 logenetic trees based on embryology which are 

 annually cut down is amazing, and in fact the 

 truth of the theory of recapitulation as applied 

 to the embryonic stages is now somewhat ques- 

 tioned. 



I do not at all regret quoting the name of 

 Francis Maitland Balfour in regard to his warn- 

 ing against placing too much reliance on pla- 

 cental arrangements as criteria for the classifi- 

 cation of the Mammalia, and hold that it applies 

 directly to the question of the systematic posi- 

 tion of Tarsius. On this side of the Atlantic 

 we do not all follow the Neo-Darwinians in 

 believing that the germinal products are locked 

 up in iron safes as it were, and not affected by 

 external conditions as the rest of the organism. 



I will now sum up my principal reasons 

 for not accepting Professor Hubrecht' s views 

 that Tarsius is only related among the Primates 

 to the Anthropoids : 



1. It has not been shown as yet that the 

 placenta in the lemurs is not a derivative of the 

 chorion as in the apes.* 



*M. A. Milne-Edwards remarks : "Or, I'allan- 

 toide des Indrisines est si facile a detacher des parties 

 adjacentes, qu'il me semble peu probable qu'il ait 

 laiss6 un de ses feuillets adherent au chorion, at il y a 

 tout lieu de penser que I'explioation mecaniqne de la 

 production du placenta, telle qu'elle a it& propos^e 

 par M. Baer et BisohoS n'est pas toujours I'expres- 

 sion de la v&it6, et que, dans certain oas au moins, 

 I'arriv^e des vaisseaux sanguins de I'allanto'ide i, la 

 face externe du chorion provoque une hypertrophie 

 dans les parties correspondantes du tissu de cette en- 

 vellope fcetal, et que c'est de cette maniere que se 

 forme le placenta, et non a la suite de I'aocolement 

 d'une portion des parois de la vesicule allantoidi- 

 enne." Mammiferes de Madagascar, p. 284. 



