210 DR. CARPENTER'S RESEARCHES ON THE FORAMINIFERA. 



40. In the specimen represented in fig. 5, the central portion appears to have been 

 lost, with about a third of the peripheral ; and the new growth seems to have taken 

 place at the same time, from the inner margin aaa of the fragment, and from its 

 outer margin b b b, the two growths becoming continuous with each other along the 

 broken edges ab, ab. For although the zones that lie internally to a a a are conform- 

 able to those which surround them, yet there is a peculiar character about them 

 (more apparent in the specimen than in the drawing) which indicates them to have 

 been formed at a later period, and to have been contemporaneous with those which 

 surround the zone b b b. Their actual continuity at the angles a a is unfortunately 

 interrupted by an injury which the specimen seems subsequently to have received; 

 yet its traces are sufficiently perceptible on one side, to justify the belief in its former 

 existence. The specimen of which fig. 4 is a delineation, seems to have been the 

 subject of several minor fractures and reparations ; but the course of its zones marks 

 out an obvious separation between an earlier- and a later-formed portion, one 

 having sprung from the other along the line ab. The incompleteness of the speci- 

 men, however, prevents me from coming to any certain conclusion, whether the 

 small inner portion is here the older, the large outer portion having grown in the 

 first instance from its margin a b, and having gradually extended itself around it; 

 or whether the outer portion is the residue of an unusually excentric disk, which, 

 having lost its nucleus and the zones immediately surrounding it, has filled up the 

 central space with an extension from its innermost zone, which is consequently the 

 newest portion of the whole. It is interesting to find evidence in fossil specimens, 

 that the same kind of reparation has taken place. Among the Orbitolites which I 

 have examined from the Calcaire grossier of Paris, is a disk of which a large part 

 had obviously been lost by fracture, but of which the original symmetry had been in 

 great degree restored by a similar outgrowth from the zones formed from the 

 uninjured margin, along the fractured edge. 



41. This series of abnormal phenomena, then, not only confirms the conclusion 

 that seemed fairly deducible from our previous examination of the normal mode of 

 growth, with regard to the independent endowments of the component segments of 

 the Orbitolite body, but also affords some additional information of much interest. 

 For we see, in the first place, that the growth of the sarcode, and the addition of new 

 parts, may take place in the direction of the centre, where a free edge is exposed at 

 the inner margin of any zone, as well as in the peripheral direction from the normal 

 outer margin. Secondly, the reparative nisus seems always to tend towards the pro- 

 duction of a disk, whose shape shall approach the circular, whatever may be the form 

 of the fragment which serves as its foundation; thus showing that, notwithstanding 

 the repetition and independence of the separate parts of these organisms, each cluster, 

 whether large or small, is an integer, having an archetypal symmetry to which it 

 tends to conform, thus strongly reminding us of the laws of crystallization. And 

 thirdly, the plan by which this recurrence to the discoidal form is provided for, 



