354 



CARL VOGT. 



LoxosoMA.^ By Carl Vogt, Professor at the University of 

 Geneva. With Plate XXII. 



The paper opens with a historical preamble, in which the Author 

 gives an account in chronological order of the various papers 

 relating to the genus Loxosoma, which have appeared from the 

 year 1863, when it was first observed by Keferstein, and almost 

 simultaneously by Claparcde, to the present time. 



A'ogt^s researches were conducted at Eoscoff, and the species 

 which he has studied is one new to science, which he has named 

 L. phascolosomattmi, and briefly characterised as follows: "Ten- 

 tacles 12 — 18. Pedal gland wanting; number of buds never 

 exceeding two.'^ It attaches itself to the pointed, caudal ex- 

 tremity of the worms {Phascolosoma elongatum and margarlta- 

 ceum), where it forms a small tuft, hardly visible to the naked 

 eye. 



Methods of Observation. 



As the Loocosomas are very firmly attached to the epidermis of 

 the wornm it is almost impossible to remove them unmutilated. 

 To observe them in sitil,\\\^ extremity of the tail bearing the tuft of 

 Poli/zoa must be cut off with a pair of scissors, and placed entire 

 under the compressor, care being being taken merely to fix and 

 not to compress the polypides. In this way the movements of 

 the Loxosomas and their mode of attachment may be readily 

 studied. But to examine them with high powers it is of course 

 necessary to detach them, and to do this, the Author recommends 

 that the extremity of the tail of the annelid, after it has been cut 

 off, should be scraped with a scalpel, and all the detritus thus 

 obtained be covered with a piece of thin glass. Amongst muti- 

 lated Loxosomas, pieces of the stem, &c., many uninjured 

 polypides, attached to fragments of the epidermis, are sure to be 

 found. These fragments serve to prevent the undue compression 

 of the animals by the glass, which merely fixes them sufficiently 

 to render it possible to draw them with the Camera lucida. 



The author has made his observations almost exclusively on 

 living animals, by means of transmitted light. Patience and 

 abundance of material have been the conditions that have 

 secured his results. All his figures have been taken with the 

 camera from living animals, and finished, as far as possible, with 

 the object before him. They are in no degree diagrammatic ; 

 " for if I have a horror of anything," he says, " it is of the 

 so called semi-diagrammatic figures, in which authors mingle 

 with the facts observed their own theoretic views, in such a 



1 " Sur le Loxosome des Phascolosomes " (' Loxoaoma Phascolosoniatum') 

 par Carl Vogt, Prof, a, I'Universite de Geneve. Translated and condensed, 

 by the llev. Thomas Hincks, F.R.S., from the 'Archives de Zoologie 

 Experimentale,' 1877. 



