SCIENTIFIC NEWS. 



[April 27, 1S8S. 



FORAMINIFERA.— I. 



BEFORE the days of defined scientific, and especially 

 microscopical research, there had been a general 

 tendency, though lessening from past to more recent 

 times, to suppose that any study which regarded natural 

 things of small size, or those that would not give up 

 their secrets of origin and habits to a casual observer, 

 must in some degree be associated with the idea of low 

 aim in intellectual work. Doubtless had Marcus 

 Aurelius lived at the present day the following would 

 not have appeared. The imperial philosopher says : — 

 " Some people are little enough to be attracted by things 

 in a state of bare existence or vegetation, as with stones, 

 wood, figs, grapes, olives, and such like. Others, who 

 are somewhat more reasonable in their fancy, must have 

 life to charm them ; and these it maybe are in love with 

 their flocks and herds. A third sort, better furnished 

 than the fortner, admire nothing beneath a rational soul." 

 It is, however, clear to all who inquire into these things 

 that, just as it would be irrational to call the work of a 

 watchmaker inferior to that of a man who worked only 

 upon cathedral clocks, so also would it be to suppose any 

 inferiority in the study of the minute or the apparently 

 simple forms of creation, when compared with those of 

 more specialised characters. 



Looking into Nature's ways of working, we can never 

 fail to notice evidences on all sides of the infinite 

 resources which have been drawn upon to furnish and 

 endow each form of animal life with perfect ability and 

 material for its existence. To no other group of animal 

 life does this apply with more force than to those crea- 

 tures called Foraminifera. They give us an instance of 

 a simple form of life, as far as our optical appliances are 

 able to inform us, constructing in very many instances a 

 shell of wonderful complexity and of excessively fine 

 textural structure. As members of the class Rhizopoda, 

 they are related to the Amoeba of our ponds, which, 

 however, have no shell substance investing the body, 

 though the allied forms Arcella and Dijflugia have a 

 partial encasement of a horny substance and of cemented 

 sandy and other materials respectively. Animals of this 

 class have in common means of locomotion and of pre- 

 hension combined, afforded by the filaments or exten- 

 sions of the body substance (protoplasm), which they 

 send forth at will, if such a primitive jelly-like creature 

 can be said to possess one. The Amoeba sends out these 

 processes finger-like, Diftlugiaand others in more slender 

 form, while the body substance of the Foraminifera is 

 exuded from the shell as a mass of filaments, ramifying, 

 and at points coalescent, perhaps surrounding some 

 minute organism. These two groups of the amosbiform 

 animals [lobosa), and the foraminiferal (rcticularia), 

 together with the Actinophrys of fresh water, and the 

 marine forms, the Polycistins (radiolaria), constitute the 

 class of Rhizopods or root-footed creatures. 



The minute shells of Foraminifera are familiar to all 

 who have possessed a microscope, but they may have 

 only been known as " pretty objects," perhaps arranged 

 in some conventional design, which before now has 

 taken the form of a street lamp. So much has yet to be 

 learned concerning the method of growth, the habitat, 

 and variation during the successive periods of the earth's 

 historj', of each of these interesting forms, that any 

 patient research will be amply repaid by the accession of 

 new facts which are sure to be made to the information 

 already gathered on this subject. 



The classification of this group has of necessity to be 

 based on the form and structure of the shell, and though 

 this at first may seem very artificial, yet on consideration 

 it will be seen to involve a good natural idea of the 

 animal itself, as far as regards structure, inasmuch as the 

 shell is generally so well permeated by and moulded 

 upon it, that a very intimate relation exists between the 

 two. 



A classification based on the arrangement of the 

 chambers was attempted by d'Orbigny in 1826, and 

 augmented by him in 1852. He formed for the Fora- 

 minifera seven orders, which were as follows : — The 

 first order of the Monostegian Foraminifera comprised 

 those in which the shell consisted only of a single cham- 

 ber, as in Lagena (fig. 11). The second, or Cyclostegian 

 order, was that in which the shell is formed by a cyclical 

 or concentric series of chambers, resulting in a disk- 

 shaped form, as in Orbitolites. In the third group of 

 Stichostegian shells we find those forms which consist 

 of chambers joined end-wise in a straight or curved line, 

 as in Nodosaria (fig. 12), Froiidicidaria, and Dentalina 

 (fig 13). The Helicostegian forms in the fourth order 

 were those in which the chambers are in a single series 

 and coiled to form a spiral shell, as in Cristdlaria (fig. 

 14), and Globigerina (fig. 16). The fifth order of Ento- 

 mostegian shells were characterised by a double series 

 of chambers coiled spirally, as in BuUmina and Uvigerina 

 (fig. 15). In the sixth order of Enallostegian shells we 

 have the chambers arranged alternately in two or three 

 rows, but not spirally, as in Textnlaria (fig. 10). The 

 seventh, and last, orderof the Agathistegian Foraminifera 

 comprised those whose chambers, each formed around a 

 central axis, encompass half the shell, as in Miliolina 



(fig- S)- 



This arrangement is now found to be of little utility, on 

 account of the graduation from one form into another, 

 which prevents the formation of distinct groups if only 

 the arrangement of the chambers be regarded, without 

 taking into consideration other points, such as the struc- 

 ture of the septa and chamber walls ; and also on account 

 of some forms possessing two, or even three, modes of 

 growth at different stages of their existence. The later 

 methods of classification include the minute structure of 

 the shell, which is often of as much importance as 

 external form. 



The shells of the Foraminifera are grouped mainly in 

 two divisions, the first of which is the Porcellaneous type, 

 characterised by a calcareous shell of a smooth texture, 

 sometimes chalky white, and not perforated on the sur- 

 face by numerable holes, as in the next group. The 

 great division of the Hyalina, or the glassy type of shell 

 structure, is recognised by the shell substance being 

 thickly perforated with numberless minute pores, or 

 tubules, through which the sarcode of the animal, when 

 alive, oozes. Intermediate in position to these groups 

 there is another, comprising the Arenaceous types, or 

 those which form their tests or investments of sand- 

 grains, comminuted shells, sponge spicules, or even the 

 shells of their own kindred compactly cemented, often 

 appearing rough on the outside, but which in many are 

 glazed internallj'. 



A general idea of the shell structure of the two groups 

 will be obtained from the drawings of median sections 

 taken through specimens of Ptneroplis (fig. 1), and 

 Marginulina (fig. 2), of the Porcellanea and Hyalina 

 respectively. The method of preparing these sections 

 will be described in the latter portion of this paper. In 



