fact that as soon as they are properly developed the large individual (the mother) loses her alimentary canal;" while from the median row are eventually derived the sexual zoids. On the hypothesis of Evolution, perplexities of this nature are just such as we might anticipate. If Life in general commenced with minute and simple forms, like those out of which all organisms, however complex, now originate; and if the transitions from these primordial units to organisms made up of groups of such units, and to higher organisms made up of groups of such groups took place by degrees; it is clear that individualities of the first and simplest order would merge gradually in those of a larger and more complex order, and these again in others of an order having still greater bulk and organization. Hence it would be impossible to say where the lower individualities ceased and the higher individualities commenced. § 73. To meet these difficulties, it has been proposed that the whole product of a single fertilized germ shall be regarded as a single individual; whether such whole product be organized into one mass, or whether it be organized into many masses that are partially or completely separate. It is urged that whether the development of the fertilized germ be continuous or discontinuous (§ 50) is a matter of secondary importance; that the totality of living tissue to which the fertilized germ gives rise in any one case, is the equivalent of the totality to which it gives rise in any other case; and that we must recognize this equivalence, whether such totality of living tissue takes a concrete or a discrete arrangement. In pursuance of this view, a zoological individual is constituted either by any such single animal as a mammal or bird, which may properly claim the title of a _zoon_, or by any such group of animals as the numerous _Medusæ_ that have been developed from the same egg, which are to be severally distinguished as _zooids_. Admitting it to be very desirable that there should be words for expressing these relations and this equivalence, it may be objected that to apply the word individual to a number of separate living bodies, is inconvenient: conflicting so much, as it does, with the ordinary conception which this word suggests. It seems a questionable use of language to say that the countless masses of _Anacharis Alsinastrum_ (now _Eloidea canadensis_) which, within these few years, have grown up in our rivers, canals, and ponds, are all parts of one individual: and yet as this plant does not seed in England, these countless masses, having arisen by discontinuous development, must be so regarded if we accept the above definition.