84 Mr. E. Wilson's Observations on the 



congregated in clusters. These granules I conceive to be the 

 first organic shape of the blastema of the liquor sanguinis. 



2. The aggregated grannies, measuring about yotW o* n °f 

 an inch in diameter, are minute masses, composed of four, five 

 or six of the preceding, or as many as can be aggregated with- 

 out leaving an unoccupied space in the centre of the mass. 

 With an imperfect focus, these granules have the appearance 

 of possessing a transparent globular nucleus, but this appear- 

 ance ceases when the focus is perfect, and then the compo- 

 nent granules are quite obvious, and the centre becomes a 

 dark point, namely, the shadow caused by the meeting of the 

 primitive granules. 



3. The nucleated granules, measuring between ^y— th and 

 Woo tn °f an mcn m diameter, are in point of construction an 

 " aggregated granule" with a single tier of " aggregated gra- 

 nules" arranged around it, so as to give the entire mass a cir- 

 cular or oval form. The central aggregated granule has now 

 become a nucleus, and at the same time has undergone other 

 changes which indicate its longer existence. For example, 

 the primitive granules composing it are denser than they were 

 originally, and they are separated from each other by a very 

 distinct interstitial space filled with a transparent and homo- 

 geneous matter. Sometimes this interstitial substance presses 

 the granules asunder equally on all sides, constituting a cir- 

 cular nucleus; but more frequently two opposite granules are 

 more widely separated than the rest, and the nucleus receives 

 an elongated form. The interstitial substance is most con- 

 spicuous at the line of junction of the nucleus with the secon- 

 dary tier of " aggregated granules," and in this situation 

 gives a defined character to the nucleus. Close observation 

 and a perfect focus render it quite obvious that the peripheral 

 tier of granules are in reality aggregated, they are lighter than 

 the shaded granules of the nucleus, and apparently softer in 

 texture. 



The nucleated granules are more or less flattened in form, 

 and present a flat surface of contact with the dermis. It is 

 the latter circumstance that gives the facility of determining 

 their mode of construction. 



4. The cells of the deep stratum of the epidermis, measu- 

 ring 3 o\y o tn to 2 j 1 oo tn °f an mcn ni tneu> l° n g diameter, are 

 the most striking feature of this layer, and may be said to be 

 its chief constituent. They originate, as is evident from their 

 structure, in the nucleated granules previously described, and 

 consist of a transparent layer added to the exterior of the 

 former; or, if 1 might be permitted to describe them as they 

 appear in their tesselated position, they are constituted by the 



