Slide showing a table of 'distribution of the primary evocator'. Slide shows a table of 'distribution of the primary evocator'. Title of table is 'table 15'. There are four columns. Column 1 includes mammals, birds, reptiles, amphibia, fishes, insects, molluscs, crustacea, worms and coelenterates. Column 2 is entitled 'weak inductions; e.g. neuroid thickenings, palisades, etc'. Column 3 is entitled 'strong neural inductions; e.g. small neural tubes or cavities'. Column 4 is entitled 'very strong neural inductions; e.g. big brains'. Late 19th to early 20th century