CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 815 



centre of the lumen. Instead of one nucleus, two or even more 

 are now present, one well formed and normal being placed nearer 

 the base, and the other or others, often shewing signs of degene- 

 ration, nearer the free end. Sometimes constrictions are seen 

 whereby the free peripheral portion of the cell, including one or 

 more of the nuclei, is apparently being separated from the basal 

 portion in which the remaining nucleus is lodged ; and occasionally 

 portions or fragments of cells, nucleated or nucleusless, may be seen 

 lying in the cavity of the alveolus. In the cell-substance, especially 

 towards the free border of the cell, are numerous oil globules of 

 various sizes as well as granules or particles of other nature ; some 

 of the larger oil globules may be seen projecting from the surface 

 as if about to be extruded from the cell ; and in the cavity of the 

 alveolus oil globules with a thinner or thicker coating of cell- 

 substance are frequently present. 



Between such a fully loaded phase, and a completely discharged 

 phase, various intermediate conditions may be observed, the cells 

 being of greater or less height, containing one nucleus only or 

 more than one, the cell-substance occupied with few or with many 

 oil globules and other granules, and the free border more or less 

 jagged. 



Putting these facts together we may draw the following con- 

 clusion, which is supported by other evidence, as to the changes 

 in the gland which characterize the loading and the discharge. 

 During loading the low flattened cell of the discharged alveolus 

 grows rapidly, elongating into the cylindrical form, and the nucleus 

 gives birth to two or more new nuclei. Meanwhile active meta- 

 bolism is going on in the cell-substance, deposits of fat as well as 

 of other substances are taking place. By what seems to be of the 

 nature of an amoeboid movement, some of the oil globules (and 

 possibly other matters) are extruded from the cell, much in the 

 same way that an amoeba extrudes its excrement. But besides 

 this, a division of the cell, that is a separation of part of the cell- 

 substance with an included nucleus, takes place, the daughter cell 

 thus thrown off passing into the alveolus to form part of the milk ; 

 or a budding of the cell occurs, part of the cell without a nucleus 

 being similarly cast off and undergoing a similar fate. In other 

 words, the secreting cell grows, loads itself with metabolic products, 

 and when loaded gives off bodily part of itself to contribute to the 

 secretion, part of the cell, and that part always retaining a nucleus, 

 remaining behind in order to secure subsequent growth and further 

 secretion. 



The secretion of milk differs from such a secretion as that of 

 saliva, and approaches the formation of sebum ( 437) inasmuch 

 as the transformed cell-substance is shed bodily to form part of 

 the milk. We say form part of the milk because this gross mode 

 of secretion is accompanied by the more ordinary mode. The cells 

 are at the same time in the more ordinary way discharging into 



