MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 361 



Whilst the conditions producing the sulculi that give detail to the cerebral 

 surface undoubtedly develop according to much more complicated arrangements of 

 forces than is the case in the production of partition films, still growing plastic, and 

 more or less spherical or ellipsoidal form of outgrowths of the cerebral cortex, would 

 tend to produce lines of fissuration following the same general laws. And, in fact, 

 when we come to examine the details of cerebral fissuration in highly complicated 

 brains, we find as a result types of sulculi which correspond in every respect to the 

 types of laminar partitions as produced by conjoined liquid films, more or less modi- 

 fied by the different physical conditions under which they are produced ; and no 

 other types are found except such as would be produced by the meeting of the 

 peripheries of masses that are developing around some centre of growth. 



In this way we have produced the triradiate and H-shaped or zygal fissures 

 which are so characteristic of highly convoluted brains. An examination of the 

 details of fissuration in different brains, especially in the orbital and frontal regions, 

 will make this evident. As examples may be studied Plate XXXVIII, figs. 13, 14 

 (a, b, c, d, e, f), 15, 16; Plate XLII, fig. 2 (1, 2, 3, 4, 5) and elsewhere. By 

 accurate measurements of the angles, curvatures and lengths of the component 

 parts of these sulculi, it is possible to locate the centres of growth or centres of the 

 pressure forces. Certainly important results can be reached by pursuing this line of 

 investigation, and indeed, already some very curious relations are apparently 

 pointed out by observations made in this line of study. 



PJROMORPHOLOGY. 



Just as the physiologist constantly seeks, remarks Geddes, to interpret the 

 phenomena of function in terms of mechanical, physical and chemical laws, so the 

 morphologist is tempted to inquire whether organic as well as mineral forms are 

 not alike reducible to simple mathematical law. And just as the crystallographer 

 constructs an ideally perfect mathematical form from an imperfect or fragmentary 

 crystal, so the morphologist has frequently attempted to reduce the complex- 

 curved surfaces of organic beings to definite mathematical expression. Canon 

 Moseby 1 succeeded in showing, by a combination of measurement and mathemati- 

 cal analysis, that the curved surface of any turbinated or discoid shell might be con- 

 sidered as generated by the revolution about the axis of the shell, of a curve, which 

 continually varied its dimensions according to the law of the logarithmic spiral. 

 For Goodsir this logarithmic spiral, now carved on his tomb, seemed a fundamental 

 expression of organic curvature and the dawn of a new epoch in natural science — 

 that of the mathematical investigation of organic form — and his own elaborate meas- 

 urements of the body, its organs, and even its component cells seemed to yield, now 

 the triangle and again the tetrahedron as the fundamental form. But such sup- 

 posed results, savoring more of the naturphilosophic than of sober mathematics, 

 could only serve to discourage further inquiry and interest in that direction. 



1 Phil. Trans., 1838. 



