1. There is the materialization which, though tangible, is not visible to ordinary physical sight. Of this nature are the unseen hands which so often clasp one’s arm or stroke one’s face at a _séance_, which sometimes carry physical objects through the air or make raps upon the table--though of course both these latter phenomena may easily be produced without a materialized hand at all. 2. There is the materialization which though visible is not tangible--the spirit-form through which one’s hand passes as through empty air. In some cases this variety is obviously misty and impalpable, but in others its appearance is so entirely normal that its solidity is never doubted until some one endeavours to grasp it. 3. There is the perfect materialization which is both visible and tangible--which not only bears the outward semblance of your departed friend, but shakes you cordially by the hand with the very clasp that you know so well. Now while there is a good deal of evidence to show that repercussion takes place under certain conditions in the case of this third kind of materialization, it is by no means so certain that it can occur with the first or second class. In the case of the boy-helper it is probable that the materialization would not be of the third type, since the greatest care is always taken not to expend more force than is absolutely necessary to produce whatever result may be required, and it is obvious that less energy would be used in the production of the more partial forms which we have called the first and second classes. The probability is that only the arm with which the boy held his little companion would be solid to the touch, and that the rest of his body, though looking perfectly natural, would have proved far less palpable if it had been tested. But, apart from this probability, there is another point to be considered. When a full materialization takes place, whether the subject be living or dead, physical matter of some sort has to be gathered together for the purpose. At a spiritualistic _séance_ this matter is obtained by drawing largely upon the etheric double of the medium--and sometimes even upon his physical body also, since cases are on record in which his weight has been very considerably decreased while manifestations of this character were taking place.