220 Dr. C. F. J. Lachmann on the Organization of Infusoria. 



A contractile space, such as I have now certainly seen in a 

 great number of the above-mentioned forms*, has not yet been 

 observed in any vegetable cell, or in the spore of an undoubted 

 plant : endeavours specially directed to this object have hitherto 

 been always futile. For this reason I believe, with A. Schneider f, 

 that we must associate these creatures which are furnished with 

 a contractile space with those which present the greatest external 

 resemblances to them, and also possess a contractile space, 

 namely the Monadince, and therefore with the animal Infusoria, 

 as long as no contractile space is found in indubitable vegetable 

 cells. 



In the Peridinia, which are furnished with flagella and cilia, 

 no contractile space has hitherto been found ; but, on the other 

 hand, in company with E. Claparede, I made some observations 

 on the Norwegian coast upon Peridinium tripus%, furca, and 

 fusuSy which promise, if pursued further, to make us acquainted 

 with the mode of reception of food. From the point of inser- 

 tion of the flagellum, on one side of the large notch, in the 

 upper part of the row of cilia, a clear canal passes into the body 

 of the animal, and dilates at the extremity to form a cavity of 

 variable diameter. The flagellum is often seen to contract 

 rapidly into a spiral form, and apparently disappear ; and not 

 unfrequently we may then succeed in perceiving that it is jerked 

 back into the above-mentioned cavity, from which it soon re- 

 turns into its previous position. Now it certainly appears worth 

 while to see whether small particles of food are not carried into 

 the cavity by this jerking-in of the flagellum. 



The dispute as to the position of the Bacillaria and ClosterincBj 



and that only a number of the Entozootic species (the Opalinee) will prove 

 to be truly astomatous. Bursaria cordiformis, Ehrbg., and B. intestinalis, 

 Ehrbg., however, are erroneously referred to the Opalinee, as they possess 

 a mouth. 



* Cohn does not consider his observation of the contractile space in 

 Chlamydomonas and Gonium as sufficient to justify our regarding these 

 creatures as animals. Besides these, E. Claparede and I observed the 

 contractile space also in Syncrypta Volvox, and then in Volvox, in which 

 its position is quite correctly described by Busk (Quart. Joura. of Micr. 

 Science, i. 1853). I can completely confirm Focke's observation of the 

 contractile space in Dinobryon Sertularia, and also found one in Euglena 

 viridis. Claparede saw it in Euglena Pleuronectes and E. Acus. The 

 detection of the contractile spaces in the Euglence is rendered particularly 

 difficult, not only by the mobility of the animal, but also by the circum- 

 stance that it lies directly over or close to the clear spot, indicated by 

 Ehrenberg as a ganglion. 



t Muller's Archiv, 1854, p. 203. 



X Numerous observations and measurements of transition forms made 

 by ourselves, as well as a number of drawings most kindly communicated 

 to us by Professor Boek of Christiania, seem to prove that P. tripus and 

 P. megaceros are not specifically distinct. 



