Wyman.] 25G r.Tmu'r,, 



poml. The right and left curves belonojing to the same niaonet will 

 not now be symmetrical with each other, but all the curves foi met! by 

 one maj^fnet will be symmetrical with those formed by the other. 



In abnormal development, if two nervous axes are formed en oppo- 

 site sides of one and the same yelk, each axis, or rather the symmet- 

 rical force, the axis of action of which corresponds with the nervous 

 axis, will distribute the organic matter under its influence without 

 coming in collision with that of the other, except near the umbilicus, 

 so that two nearly perfect embryos will be formed, as in the case of 

 the Siamese twins. 



If tlie two axes are formed side by side, and so near to each other 

 that the particles under their respective influence come in contact, 

 then at tiie line of contact a series of intermediate organs or limbs, 

 will be formed in connection witli the two axes, as is commonly seen 

 in those double monsters which present Avhat is called lateral doubling. 

 Here, too, as in the case of the double magnetic curves, the ri ^ht and 

 left parts connected with one and the same nervous axis will no longer 

 be symmetrical with each other, but those connected with the right 

 half of one axis will be symmetrical with those connected with the 

 left half of the other, or in otlier words, the two bodies thus united 

 will be symmetrical with each other, but will not be bilaterady sym- 

 metrical in themselves. 



If the magnets are now inclined towards each other (Fig. G, C), so 

 as tp touch at one end, forming a V, tlien we shall have the j articles 

 arranged so as to produce a figure double at one end, but single at the 

 other. The ends of the magnets which are separated will arrange 

 their ])articles so as to form a double series of cur\es, which are com- 

 pletely independent of each other ; but as the magnets comt nearer 

 together the intervening curves are gradually modified or sup iressed, 

 and at last a single symmetrical terminal figure is formed. One half 

 of this terminal portion is however formed under the influence of the 

 right, and the other of the left magnet. 



Likewise in certain double embryos if the axes are inclin jd so as 

 to form a V-shaped figure, the two separated ends will have a head 

 more or less complete, but as the two axes converge below, the or- 

 gans become more or less fused and suppressed, and at length the 

 hindmost are reduced to the normal type, all intermediate ones having 

 become obsolete. Tlie body will be provided with two legs, but one 

 will be connected with, and under the control of the right axis, and 

 the other under that of the left. Precisely such a case is found in 

 the well known instance of Ritta-Christina. The completeness of the 

 intermediate organs in a given instance, as in the case of the inter- 

 mediate magnetic curves, will depend upon the degree of divergence 

 or separation of the axes. 



