(2) With very few exceptions, the polyp is not the only type of individual that occurs, but alternates in the life-cycle of a given species, with a distinct type, the medusa, while in other cases the polyp-stage may be absent altogether, so that only medusa-individuals occur in the life-cycle.
In other gallflies and in aphids we find that a sexual generation alternates with one or with many virgin generations.
The plants are admirably adapted for climates in which a season favourable to growth alternates with a hot or dry season;.
Mountain alternates with valley, so that not more than one-eighth of the countrys entire area is cultivable.
And hence I found the required area of the circular segment 2 x3 A x5 il-A to be x - 5 - 7, &c. And in the same manner might be 3 produced the interpolated areas of other curves; as also the area of the hyperbola and the other alternates in this series (1 - (i+xx) 1, (1 --xx) I, &c....
How would you define alternates? Add your definition here.