218 GENERAL HISTORY OF THE INFUSORIA. 



takes place by the extrusion of the sarcode through the marginal pores, so 

 as to form a complete annulus, thickened at intervals into segments, and nar- 

 rowed between these into connecting stolons, the shell being probably pro- 

 duced by the calcification of theii' outer portions. 



Since the above account was ^viitten, Schultze has produced a supple- 

 mentaiy sheet detailing further observations on the development of Forami- 

 niffera {Bericht der Naturforschenden GeseUschaft in Hcdle, 11th August, 

 1855). 



Having met mth some large specimens of TrUocidina ^"' in diameter and 

 without a tooth in the oral aperture, he kept them for a length of time under 

 observation. Those which remained adherent to the sides of the glass vessel for 

 eight to foui^teen days mostly became invested with a brownish slimy matter, 

 which more or less completely obscui-ed the view of the external characters of the 

 shell. After some more days had elapsed, the lens brought into view a num- 

 ber of small, round, sharply- defined coi'puscles, which loosened themselves from 

 the soft enveloping mass, and gradually diverged fi^om one another imtil some 

 forty were visible. On removing these, and placing them imder the microscope, 

 they proved to be young Mdiolidce, with their process outstretched. Inter- 

 nally, neither vacuoles, cells, nor contractile vesicle, nor a nucleus could be 

 detected. 



The brief abstract of Dr. Carpenter's elaborate essay (read before the Royal 

 Society, 1855) furnishes us also with the following memorandum of hisAiews 

 regarding the reproduction of Foraminifera, "svith especial reference to Orbi- 

 tolites. " He is only able to suggest that certain minute spherical masses of 

 sarcode with which some of the cells are filled may be gemmides, and that 

 other bodies enclosed in firm envelopes which he has more rarely met with, but 

 which seem to break their way out of the superficial ceUsj may be ova." Mr. 

 Jeffrey's views {Proceedings of JRoyal Society, 1855) do not quite coincide. 

 Dr. Carpenter's '' idea of their reproduction by gemmation," he says, " is also 

 probably correct, although I cannot agree with him in considering the granules 

 which are occasionally found in the ceUs as ova. These bodies I have fre- 

 quently noticed, especially in the Lagence ; but they appeared to constitute the 

 entire mass, and not merely a part, of the animal. I am inclined to think 

 they are only desiccated portions of the animal separated from each other in 

 consequence of the absence of any muscular or nervous structui'e. It may 

 also be questionable if the term ' ova ' is rightly applicable to any animal 

 which has no distinct organs of any kind. Possibly the fry may pass through 

 a metamorphosis, as in the case of the Medusce.^' 



Of the many Amcehce seen in company with Foraminifera, the A. por recta 

 is particularly remarkable, and might easily pass for one of the latter when 

 young and destitute of its shell ; for its processes resemble those of Mdiolidce 

 and Rotcdidce in delicacy and extensibility and in the cmTent of granules 

 which passes through them. This circumstance suggests the possible deriva- 

 tion of testaceous Rhizopoda from the naked forms ; and if we recall to mind the 

 black globules sui-mised to be germs, their j^rimary transformation into Amoehce 

 is imaginable, and the whole cycle of development of Foraminifera becomes 

 thereupon explicable. *' However, I must," says Schultze, " confess that this 

 change of the black spheres into AmoebcB is a further argument against their 

 nature as germs, since between these granular bodies, so imaffected by che- 

 mical agents, and Kmoehce no intermediate link is discoverable. 



Of the Shells of Testaceous Rhizopoda. a. Shells of Monothalamia. — 

 The family ArcelUna (Ehr.) corresponds in most points with the section Mono- 

 thalamia of Schultze. The Berlin Professor, however, believed that his family 

 Areellina and the Polythalamia belonged to entirely different classes of ani- 



