Chapter XV — 179 — Origin of Vacuoles 



are never formed de novo, but always arise by the division of pre- 

 existing vacuoles, and are transmitted by division from cell to cell. 

 But the Dangeards believe that it is not the vacuole itself, that is 

 transmitted, but the metachromatin, which they consider to be the 

 universal substance of their vacuome. According to them, this 

 metachromatin persists in a solid state after the disappearance of 

 the vacuole in the seed, as well as in the spores of fungi, and re- 

 forms vacuoles anew at germination by taking in water again. 

 This theory is difficult to admit in view of the fact that we know 

 that there is no single chemical substance which is characteristic 

 of vacuoles. 



Actually, it is extremely difficult to study the origin of vacuoles 

 in the phanerogams because of the great number, and the small 

 size, of these elements in embryonic cells. It is known, moreover, 

 from what has just been said that vacuoles exist in all cells and 

 that they are capable of dividing and of fragmenting. It has been 

 observed besides that during mitosis the vacuoles are distributed 

 between two daughter cells. It is for this reason that Bailey and 

 ZiRKLE, without committing themselves on this subject, say that 

 they have never seen vacuoles form de novo and that nothing 

 proves that this phenomenon is possible. But neither the fact of 

 the distribution of the vacuoles between the daughter cells during 

 mitosis, nor that of their persistence in the aleurone grains of the 

 seed and their transmission to the embryo, proves that the vacuoles 

 can not rise de novo. Moreover, we can scarcely permit ourselves 

 to consider them as individualities of the cell, incapable of forming 

 de novo, when through their extreme instability of form, they may 

 in the space of a few minutes be split up into very minute elements 

 capable soon of fusing again. 



Some fungi are more favorable for the study of the origin of 

 the vacuoles than are the phanerogams. In the mycelium of Peni- 

 cillium glaucum (Fig. 101) or of Oidium lactis, for example, lateral 

 branches may be observed to form from filaments already con- 

 taining large vacuoles and in these branches, which at first do not 

 have them, small globular vacuoles are seen to appear which can 

 hardly have any relation to the large vacuole of the filament from 

 which the branch arises. This is also true of the buds of the 

 yeasts in which there are small vacuoles which do not appear to 

 be derived from the large vacuole of the mother cell. We concluded 

 from these very clear facts observed by means of vital dyes that 

 vacuoles may be formed de novo (Figs. 124-126). 



P. Dangeard has objected, and with reason, that vital stains 

 can cause alterations of the vacuoles, for example, their immedi- 

 ate fragmentation when in the process of dividing. It is certain 

 that vital dyes stop the multiplication of cells in certain cases, par- 

 ticularly in the fungi. Dangeard again took up the study of the 

 formation of vacuoles in yeasts and in following the budding of 

 these fungi in a moist chamber without vital staining, showed that 

 the large vacuole of the mother cell always puts out a delicate pro- 

 longation into the bud. The extremity of this prolongation is cut 



