892 THE ANIMAL KINGDOM. 



minute young with calcareous tests, single-chambered in Miliolina, Spirillina 

 and Peneroplis, three-chambered in the Rotalid, with the first ring of 

 chambers complete in Orbitolites. Similar young of Miliolina and Rotalia 

 have been found free, and been proved to be uninucleate by Hertwig, the 

 nucleus lying in the primordial chamber of the Rotaliae. There can be 

 little doubt that the young in question take origin by the multiplication of 

 the nucleus, the separation of protoplasm round the nuclei thus formed, 

 and the deposition of a test ; they are then set free at the aperture of the 

 parental test, or, if this is represented by pores, as in Peneroplis, by solu- 

 tion of the walls of the chambers containing them 1 . 



A colonial state occurs in Microgromia socialis, where a number of 

 individuals remain united by their pseudopodia. When the latter contract, 

 as they do on irritation, the tests are drawn into a heap, and in this con- 

 dition the organism was described by Archer as Cystophrys Haeckeliana, in 

 its expanded state as Gromia socialis. Young Miliolinae were observed by 

 Hertwig associated to the number of 30-40 by a protoplasmic mass, from 

 which pseudopodia streamed in all directions. Conjugation has not been 

 observed, unless the apposition of young Miliolinae in twos, recorded by 

 Gervais, is an instance. 



The majority of Foraminifera are marine, but some of the marine 

 species are capable of living in brackish water, with very slight admixture 

 of salt, and two (Polystomella striatopunctata^ Nonionina depressula) have 

 been gathered even in perfectly fresh. Microgromia and Diaphoropodon 

 are entirely freshwater, Lieberkiihnia and Gromia inhabit both fresh and 

 salt. One species, Entzia tetrastomella, has been found in salt pools in 

 Transylvania. The only terricolous form known, Gromia terricola, was 



1 Ray Lankester found in the anterior part of Haliphysema Tumanowiczii nucleated egg-like 

 bodies (Q. J. M. xix. p. 482), and Saville Kent describes in the same Foraminifer minute amoebi- 

 form young, naked pyriform bodies, and every stage to the adult (A. N. H. (5), ii. p. 76). It is 

 possible that the ' ova ' described by some older authorities in various genera are young in an 

 early stage. The protoplasm of the parent may or may not be completely used up in the repro- 

 ductive process. In Orbitolites the young lie in the peripheral annulus, the outer wall of which is 

 described by W. B. Carpenter as very thin, and its cavity undivided by septa into chamberlets. 

 The number of young is sometimes very great, e. g. in a Peneroplis Proteus described by Schacko 

 it was 118, all contained in the fourteen terminal chambers. Many specimens of the Globigerinid 

 Orbulina, which has the form of a perfect sphere, with, in some instances, an aperture, contain 

 adherent to the inner surface a Globigerina with a number of chambers, up to 13-14, the larger 

 chambers being spinulose. Such inclosures are most common in small and middle-sized specimens, 

 whilst in large they are either absent or scarcely indicated ; they are found both in recent and fossil 

 specimens. Three theories have been proposed to account for the phenomenon : (i) that Orbulina 

 is the terminal chamber of a Globigerina which has undergone complete involution, and is gradually 

 absorbed ; (2) that the Globigerina is developed within the Orbulina from a germ which has not 

 been set free (Schacko, A. N. 49 (i), 1883, p. 437) ; (3) that the Orbulina is the initial, i. e. pri- 

 mordial chamber of a Globigerina^ other chambers having been developed within it, and the case 

 being one of dimorphism (Schlumberger, A. N. H. (5), xiv. 1884, P- 7)- The figures and descrip- 

 tions given by Shacko appear to be directly contradictory of Schlumberger's theory. Siddall has 

 described curious disruptive phenomena in Shepheardella, which appear to be reproductive see his 

 paper, Q. J. M. xx. 1880. 



